Python API¶

This section includes information for using the Python API of bob.measure.

Measurement¶

Classification¶

`bob.measure.correctly_classified_negatives`(…)	This method returns an array composed of booleans that pin-point, which
`bob.measure.correctly_classified_positives`(…)	This method returns an array composed of booleans that pin-point, which

Single point measurements¶

`bob.measure.farfrr`((negatives, positives, …)	Calculates the false-acceptance (FA) ratio and the false-rejection (FR)
`bob.measure.f_score`((negatives, positives, …)	This method computes the F-score of the accuracy of the classification
`bob.measure.precision_recall`((negatives, …)	Calculates the precision and recall (sensitiveness) values given
`bob.measure.recognition_rate`(cmc_scores[, …])	Calculates the recognition rate from the given input
`bob.measure.detection_identification_rate`(…)	Computes the detection and identification rate for the given threshold.
`bob.measure.false_alarm_rate`(cmc_scores, …)	Computes the false alarm rate for the given threshold,.
`bob.measure.eer_rocch`((negatives, …)	Calculates the equal-error-rate (EER) given the input data, on the ROC

Thresholds¶

`bob.measure.eer_threshold`((negatives, …)	Calculates the threshold that is as close as possible to the
`bob.measure.rocch2eer`((pmiss_pfa) -> threshold)	Calculates the threshold that is as close as possible to the
`bob.measure.min_hter_threshold`((negatives, …)	Calculates the `bob.measure.min_weighted_error_rate_threshold()`
`bob.measure.min_weighted_error_rate_threshold`(…)	Calculates the threshold that minimizes the error rate for the given
`bob.measure.far_threshold`((negatives, …)	Computes the threshold such that the real FAR is at most the
`bob.measure.frr_threshold`((negatives, …)	Computes the threshold such that the real FRR is at most the

Curves¶

`bob.measure.roc`((negatives, positives, …)	Calculates points of an Receiver Operating Characteristic (ROC)
`bob.measure.rocch`((negatives, …)	Calculates the ROC Convex Hull (ROCCH) curve given a set of positive
`bob.measure.roc_for_far`((negatives, …)	Calculates the ROC curve for a given set of positive and negative
`bob.measure.det`((negatives, positives, …)	Calculates points of an Detection Error-Tradeoff (DET) curve
`bob.measure.epc`((dev_negatives, …)	Calculates points of an Expected Performance Curve (EPC)
`bob.measure.precision_recall_curve`(…)	Calculates the precision-recall curve given a set of positive and
`bob.measure.cmc`(cmc_scores)	Calculates the cumulative match characteristic (CMC) from the given input.

Generic¶

`bob.measure.ppndf`((value) -> ppndf)	Returns the Deviate Scale equivalent of a false rejection/acceptance
`bob.measure.relevance`(input, machine)	Calculates the relevance of every input feature to the estimation process
`bob.measure.mse`(estimation, target)	Mean square error between a set of outputs and target values
`bob.measure.rmse`(estimation, target)	Calculates the root mean square error between a set of outputs and target
`bob.measure.get_config`()	Returns a string containing the configuration information.

Loading data¶

`bob.measure.load.open_file`(filename[, mode])	Opens the given score file for reading.
`bob.measure.load.scores`((filename[, ncolumns])	Loads the scores from the given score file and yield its lines.
`bob.measure.load.split`((filename[, ncolumns])	Loads the scores from the given score file and splits them into positives and negatives.
`bob.measure.load.cmc`((filename[, ncolumns])	Loads scores to compute CMC curves.
`bob.measure.load.four_column`(filename)	Loads a score set from a single file and yield its lines
`bob.measure.load.split_four_column`(filename)	Loads a score set from a single file and splits the scores
`bob.measure.load.cmc_four_column`(filename)	Loads scores to compute CMC curves from a file in four column format.
`bob.measure.load.five_column`(filename)	Loads a score set from a single file and yield its lines
`bob.measure.load.split_five_column`(filename)	Loads a score set from a single file and splits the scores
`bob.measure.load.cmc_five_column`(filename)	Loads scores to compute CMC curves from a file in five column format.

Calibration¶

`bob.measure.calibration.cllr`(negatives, …)	Cost of log likelihood ratio as defined by the Bosaris toolkit
`bob.measure.calibration.min_cllr`(negatives, …)	Minimum cost of log likelihood ratio as defined by the Bosaris toolkit

Plotting¶

`bob.measure.plot.roc`(negatives, positives[, …])	Plots Receiver Operating Characteristic (ROC) curve.
`bob.measure.plot.det`(negatives, positives[, …])	Plots Detection Error Trade-off (DET) curve as defined in the paper:
`bob.measure.plot.det_axis`(v, **kwargs)	Sets the axis in a DET plot.
`bob.measure.plot.epc`(dev_negatives, …[, …])	Plots Expected Performance Curve (EPC) as defined in the paper:
`bob.measure.plot.precision_recall_curve`(…)	Plots a Precision-Recall curve.
`bob.measure.plot.cmc`(cmc_scores[, logx])	Plots the (cumulative) match characteristics and returns the maximum rank.
`bob.measure.plot.detection_identification_curve`(…)	Plots the Detection & Identification curve over the FAR

OpenBR conversions¶

`bob.measure.openbr.write_matrix`(score_file, …)	Writes the OpenBR matrix and mask files (version 2), given a score file.
`bob.measure.openbr.write_score_file`(…[, …])	Writes the Bob score file in the desired format from OpenBR files.

Details¶

bob.measure.mse(estimation, target)[source]¶

Mean square error between a set of outputs and target values

Uses the formula:

\[MSE(\hat{\Theta}) = E[(\hat{\Theta} - \Theta)^2]\]

Estimation (\(\hat{\Theta}\)) and target (\(\Theta\)) are supposed to have 2 dimensions. Different examples are organized as rows while different features in the estimated values or targets are organized as different columns.

Parameters:	estimation (array) – an N-dimensional array that corresponds to the value estimated by your procedure target (array) – an N-dimensional array that corresponds to the expected value
Returns:	The average of the squared error between the estimated value and the target
Return type:	float

bob.measure.rmse(estimation, target)[source]¶

Calculates the root mean square error between a set of outputs and target

Uses the formula:

\[RMSE(\hat{\Theta}) = \sqrt(E[(\hat{\Theta} - \Theta)^2])\]

Estimation (\(\hat{\Theta}\)) and target (\(\Theta\)) are supposed to have 2 dimensions. Different examples are organized as rows while different features in the estimated values or targets are organized as different columns.

Parameters:	estimation (array) – an N-dimensional array that corresponds to the value estimated by your procedure target (array) – an N-dimensional array that corresponds to the expected value
Returns:	The square-root of the average of the squared error between the estimated value and the target
Return type:	float

bob.measure.relevance(input, machine)[source]¶

Calculates the relevance of every input feature to the estimation process

Uses the formula:

Neural Triggering System Operating on High Resolution Calorimetry Information, Anjos et al, April 2006, Nuclear Instruments and Methods in Physics Research, volume 559, pages 134-138

\[R(x_{i}) = |E[(o(x) - o(x|x_{i}=E[x_{i}]))^2]|\]

In other words, the relevance of a certain input feature i is the change on the machine output value when such feature is replaced by its mean for all input vectors. For this to work, the input parameter has to be a 2D array with features arranged column-wise while different examples are arranged row-wise.

Parameters:	input (array) – an N-dimensional array that corresponds to the value estimated by your model machine (object) – A machine that can be called to “process” your input
Returns:	An 1D float array as large as the number of columns (second dimension) of your input array, estimating the “relevance” of each input column (or feature) to the score provided by the machine.
Return type:	array

bob.measure.recognition_rate(cmc_scores, threshold=None, rank=1)[source]¶

Calculates the recognition rate from the given input

It is identical to the CMC value for the given rank.

The input has a specific format, which is a list of two-element tuples. Each of the tuples contains the negative \(\{S_p^-\}\) and the positive \(\{S_p^+\}\) scores for one probe item \(p\), or None in case of open set recognition. To read the lists from score files in 4 or 5 column format, please use the bob.measure.load.cmc_four_column() or bob.measure.load.cmc_five_column() function.

If threshold is set to None, the rank 1 recognition rate is defined as the number of test items, for which the highest positive \(\max\{S_p^+\}\) score is greater than or equal to all negative scores, divided by the number of all probe items \(P\):

\[\begin{split}\mathrm{RR} = \frac{1}{P} \sum_{p=1}^{P} \begin{cases} 1 & \mathrm{if } \max\{S_p^+\} >= \max\{S_p^-\}\\ 0 & \mathrm{otherwise} \end{cases}\end{split}\]

For a given rank \(r>1\), up to \(r\) negative scores that are higher than the highest positive score are allowed to still count as correctly classified in the top \(r\) rank.

If threshold \(\theta\) is given, all scores below threshold will be filtered out. Hence, if all positive scores are below threshold \(\max\{S_p^+\} < \theta\), the probe will be misclassified at any rank.

For open set recognition, i.e., when there exist a tuple including negative scores without corresponding positive scores (None), and all negative scores are below threshold \(\max\{S_p^+\} < \theta\), the probe item is correctly rejected, and it does not count into the denominator \(P\). When no threshold is provided, the open set probes will always count as misclassified, regardless of the rank.

Parameters:	cmc_scores (`list`) – A list in the format `[(negatives, positives), ...]` containing the CMC scores loaded with one of the functions (`bob.measure.load.cmc_four_column()` or `bob.measure.load.cmc_five_column()`). Each pair contains the `negative` and the `positive` scores for one probe item. Each pair can contain up to one empty array (or `None`), i.e., in case of open set recognition. threshold (`float`, optional) – Decision threshold. If not `None`, all scores will be filtered by the threshold. In an open set recognition problem, all open set scores (negatives with no corresponding positive) for which all scores are below threshold, will be counted as correctly rejected and removed from the probe list (i.e., the denominator). rank (`int`, optional) – The rank for which the recognition rate should be computed, 1 by default.
Returns:	The (open set) recognition rate for the given rank, a value between 0 and 1.
Return type:	float

bob.measure.cmc(cmc_scores)[source]¶

Calculates the cumulative match characteristic (CMC) from the given input.

The input has a specific format, which is a list of two-element tuples. Each of the tuples contains the negative and the positive scores for one probe item. To read the lists from score files in 4 or 5 column format, please use the bob.measure.load.cmc_four_column() or bob.measure.load.cmc_five_column() function.

For each probe item the probability that the rank \(r\) of the positive score is calculated. The rank is computed as the number of negative scores that are higher than the positive score. If several positive scores for one test item exist, the highest positive score is taken. The CMC finally computes how many test items have rank r or higher, divided by the total number of test values.

Note

The CMC is not available for open set classification. Please use the detection_identification_rate() and false_alarm_rate() instead.

Parameters:

cmc_scores (list) –

A list in the format [(negatives, positives), ...] containing the CMC scores loaded with one of the functions bob.measure.load.cmc_four_column(), bob.measure.load.cmc_five_column(), or bob.measure.load.cmc().

Each pair contains the negative and the positive scores for one probe item. Each pair can contain up to one empty array (or None), i.e., in case of open set recognition.

Returns: A 1D float array representing the CMC curve. The rank 1 recognition rate can be found in array[0], rank 2 rate in array[1], and so on. The number of ranks (array.shape[0]) is the number of gallery items. Values are in range [0,1].

Return type: 1D numpy.ndarray of float

bob.measure.detection_identification_rate(cmc_scores, threshold, rank=1)[source]¶

Computes the detection and identification rate for the given threshold.

This value is designed to be used in an open set identification protocol, and defined in Chapter 14.1 of [LiJain2005].

Although the detection and identification rate is designed to be computed on an open set protocol, it uses only the probe elements, for which a corresponding gallery element exists. For closed set identification protocols, this function is identical to recognition_rate(). The only difference is that for this function, a threshold for the scores need to be defined, while for recognition_rate() it is optional.

Parameters:	cmc_scores (`list`) – A list in the format `[(negatives, positives), ...]` containing the CMC scores loaded with one of the functions (`bob.measure.load.cmc_four_column()` or `bob.measure.load.cmc_five_column()`). Each pair contains the `negative` and the `positive` scores for one probe item. Each pair can contain up to one empty array (or `None`), i.e., in case of open set recognition. threshold (float) – The decision threshold \(\tau`\). rank (`int`, optional) – The rank for which the curve should be plotted
Returns:	The detection and identification rate for the given threshold.
Return type:	float

bob.measure.false_alarm_rate(cmc_scores, threshold)[source]¶

Computes the false alarm rate for the given threshold,.

This value is designed to be used in an open set identification protocol, and defined in Chapter 14.1 of [LiJain2005].

The false alarm rate is designed to be computed on an open set protocol, it uses only the probe elements, for which no corresponding gallery element exists.

Parameters:	cmc_scores (`list`) – A list in the format `[(negatives, positives), ...]` containing the CMC scores loaded with one of the functions (`bob.measure.load.cmc_four_column()` or `bob.measure.load.cmc_five_column()`). Each pair contains the `negative` and the `positive` scores for one probe item. Each pair can contain up to one empty array (or `None`), i.e., in case of open set recognition. threshold (float) – The decision threshold \(\tau`\).
Returns:	The false alarm rate.
Return type:	float

bob.measure.get_config()[source]¶: Returns a string containing the configuration information.

bob.measure.correctly_classified_negatives(negatives, threshold) → classified¶

This method returns an array composed of booleans that pin-point, which negatives where correctly classified for the given threshold

The pseudo-code for this function is:

foreach (k in negatives) if negatives[k] < threshold: classified[k] = true else: classified[k] = false

Parameters:

negatives : array_like(1D, float)

The scores generated by comparing objects of different classes

threshold : float

The threshold, for which scores should be considered to be correctly classified

Returns:

classified : array_like(1D, bool)

The decision for each of the negatives

bob.measure.correctly_classified_positives(positives, threshold) → classified¶

This method returns an array composed of booleans that pin-point, which positives where correctly classified for the given threshold

The pseudo-code for this function is:

foreach (k in positives) if positives[k] >= threshold: classified[k] = true else: classified[k] = false

Parameters:

positives : array_like(1D, float)

The scores generated by comparing objects of the same classes

threshold : float

The threshold, for which scores should be considered to be correctly classified

Returns:

classified : array_like(1D, bool)

The decision for each of the positives

bob.measure.det(negatives, positives, n_points) → curve¶

Calculates points of an Detection Error-Tradeoff (DET) curve

Calculates the DET curve given a set of negative and positive scores and a desired number of points. Returns a two-dimensional array of doubles that express on its rows:

[0] X axis values in the normal deviate scale for the false-accepts

[1] Y axis values in the normal deviate scale for the false-rejections

You can plot the results using your preferred tool to first create a plot using rows 0 and 1 from the returned value and then replace the X/Y axis annotation using a pre-determined set of tickmarks as recommended by NIST. The derivative scales are computed with the bob.measure.ppndf() function.

Parameters:

negatives, positives : array_like(1D, float)

The list of negative and positive scores to compute the DET for

n_points : int

The number of points on the DET curve, for which the DET should be evaluated

Returns:

curve : array_like(2D, float)

The DET curve, with the FAR in the first and the FRR in the second row

bob.measure.eer_rocch(negatives, positives) → threshold¶

Calculates the equal-error-rate (EER) given the input data, on the ROC Convex Hull (ROCCH)

It replicates the EER calculation from the Bosaris toolkit (https://sites.google.com/site/bosaristoolkit/).

Parameters:

negatives, positives : array_like(1D, float)

The set of negative and positive scores to compute the threshold

Returns:

threshold : float

The threshold for the equal error rate

bob.measure.eer_threshold(negatives, positives[, is_sorted]) → threshold¶

Calculates the threshold that is as close as possible to the equal-error-rate (EER) for the given input data

The EER should be the point where the FAR equals the FRR. Graphically, this would be equivalent to the intersection between the ROC (or DET) curves and the identity.

Note

The scores will be sorted internally, requiring the scores to be copied. To avoid this copy, you can sort both sets of scores externally in ascendant order, and set the is_sorted parameter to True

Parameters:

negatives, positives : array_like(1D, float)

The set of negative and positive scores to compute the threshold

is_sorted : bool

[Default: False] Are both sets of scores already in ascendantly sorted order?

Returns:

threshold : float

The threshold (i.e., as used in bob.measure.farfrr()) where FAR and FRR are as close as possible

bob.measure.epc(dev_negatives, dev_positives, test_negatives, test_positives, n_points[, is_sorted][, thresholds]) → curve¶

Calculates points of an Expected Performance Curve (EPC)

Calculates the EPC curve given a set of positive and negative scores and a desired number of points. Returns a two-dimensional numpy.ndarray of type float with the shape of (2, points) or (3, points) depending on the thresholds argument. The rows correspond to the X (cost), Y (weighted error rate on the test set given the min. threshold on the development set), and the thresholds which were used to calculate the error (if the thresholds argument was set to True), respectively. Please note that, in order to calculate the EPC curve, one needs two sets of data comprising a development set and a test set. The minimum weighted error is calculated on the development set and then applied to the test set to evaluate the weighted error rate at that position.

The EPC curve plots the HTER on the test set for various values of ‘cost’. For each value of ‘cost’, a threshold is found that provides the minimum weighted error (see bob.measure.min_weighted_error_rate_threshold()) on the development set. Each threshold is consecutively applied to the test set and the resulting weighted error values are plotted in the EPC.

The cost points in which the EPC curve are calculated are distributed uniformly in the range \([0.0, 1.0]\).

Note

It is more memory efficient, when sorted arrays of scores are provided and the is_sorted parameter is set to True.

Parameters:

dev_negatives, dev_positives, test_negatives, test_positives : array_like(1D, float)

The scores for negatives and positives of the development and test set

n_points : int

The number of weights for which the EPC curve should be computed

is_sorted : bool

[Default: False] Set this to True if the scores are already sorted. If False, scores will be sorted internally, which will require more memory

thresholds : bool

[Default: False] If True the function returns an array with the shape of (3, points) where the third row contains the thresholds that were calculated on the development set.

Returns:

curve : array_like(2D, float)

The EPC curve, with the first row containing the weights and the second row containing the weighted errors on the test set. If thresholds is True, there is also a third row which contains the thresholds that were calculated on the development set.

bob.measure.f_score(negatives, positives, threshold[, weight]) → f_score¶

This method computes the F-score of the accuracy of the classification

The F-score is a weighted mean of precision and recall measurements, see bob.measure.precision_recall(). It is computed as:

\[\mathrm{f-score} = (1 + w^2)\frac{\mathrm{precision}\cdot{}\mathrm{recall}}{w^2\cdot{}\mathrm{precision} + \mathrm{recall}}\]

The weight \(w\) needs to be non-negative real value. In case the weight parameter is 1 (the default), the F-score is called F1 score and is a harmonic mean between precision and recall values.

Parameters:

negatives, positives : array_like(1D, float)

The set of negative and positive scores to compute the precision and recall

threshold : float

The threshold to compute the precision and recall for

weight : float

[Default: 1] The weight \(w\) between precision and recall

Returns:

f_score : float

The computed f-score for the given scores and the given threshold

bob.measure.far_threshold(negatives, positives[, far_value][, is_sorted]) → threshold¶

Computes the threshold such that the real FAR is at most the requested far_value if possible

Note

The scores will be sorted internally, requiring the scores to be copied. To avoid this copy, you can sort the negatives scores externally in ascendant order, and set the is_sorted parameter to True

Parameters:

negatives : array_like(1D, float)

The set of negative scores to compute the FAR threshold

positives : array_like(1D, float)

Ignored, but needs to be specified – may be given as []

far_value : float

[Default: 0.001] The FAR value, for which the threshold should be computed

is_sorted : bool

[Default: False] Set this to True if the negatives are already sorted in ascending order. If False, scores will be sorted internally, which will require more memory

Returns:

threshold : float

The threshold such that the real FAR is at most far_value

bob.measure.farfrr(negatives, positives, threshold) → far, frr¶

Calculates the false-acceptance (FA) ratio and the false-rejection (FR) ratio for the given positive and negative scores and a score threshold

positives holds the score information for samples that are labeled to belong to a certain class (a.k.a., ‘signal’ or ‘client’). negatives holds the score information for samples that are labeled not to belong to the class (a.k.a., ‘noise’ or ‘impostor’). It is expected that ‘positive’ scores are, at least by design, greater than ‘negative’ scores. So, every ‘positive’ value that falls bellow the threshold is considered a false-rejection (FR). negative samples that fall above the threshold are considered a false-accept (FA).

Positives that fall on the threshold (exactly) are considered correctly classified. Negatives that fall on the threshold (exactly) are considered incorrectly classified. This equivalent to setting the comparison like this pseudo-code:

foreach (positive as K) if K < threshold: falseRejectionCount += 1

foreach (negative as K) if K >= threshold: falseAcceptCount += 1

The output is in form of a tuple of two double-precision real numbers. The numbers range from 0 to 1. The first element of the pair is the false-accept ratio (FAR), the second element the false-rejection ratio (FRR).

The threshold value does not necessarily have to fall in the range covered by the input scores (negatives and positives altogether), but if it does not, the output will be either (1.0, 0.0) or (0.0, 1.0), depending on the side the threshold falls.

It is possible that scores are inverted in the negative/positive sense. In some setups the designer may have setup the system so ‘positive’ samples have a smaller score than the ‘negative’ ones. In this case, make sure you normalize the scores so positive samples have greater scores before feeding them into this method.

Parameters:

negatives : array_like(1D, float)

The scores for comparisons of objects of different classes

positives : array_like(1D, float)

The scores for comparisons of objects of the same class

threshold : float

The threshold to separate correctly and incorrectly classified scores

Returns:

far : float

The False Accept Rate (FAR) for the given threshold

frr : float

The False Reject Rate (FRR) for the given threshold

bob.measure.frr_threshold(negatives, positives[, frr_value][, is_sorted]) → threshold¶

Computes the threshold such that the real FRR is at most the requested frr_value if possible

Note

The scores will be sorted internally, requiring the scores to be copied. To avoid this copy, you can sort the positives scores externally in ascendant order, and set the is_sorted parameter to True

Parameters:

negatives : array_like(1D, float)

Ignored, but needs to be specified – may be given as []

positives : array_like(1D, float)

The set of positive scores to compute the FRR threshold

frr_value : float

[Default: 0.001] The FRR value, for which the threshold should be computed

is_sorted : bool

[Default: False] Set this to True if the positives are already sorted in ascendant order. If False, scores will be sorted internally, which will require more memory

Returns:

threshold : float

The threshold such that the real FRR is at most frr_value

bob.measure.min_hter_threshold(negatives, positives[, is_sorted]) → threshold¶

Calculates the bob.measure.min_weighted_error_rate_threshold() with cost=0.5

Parameters:

negatives, positives : array_like(1D, float)

The set of negative and positive scores to compute the threshold

is_sorted : bool

[Default: False] Are both sets of scores already in ascendantly sorted order?

Returns:

threshold : float

The threshold for which the weighted error rate is minimal

bob.measure.min_weighted_error_rate_threshold(negatives, positives, cost[, is_sorted]) → threshold¶

Calculates the threshold that minimizes the error rate for the given input data

The cost parameter determines the relative importance between false-accepts and false-rejections. This number should be between 0 and 1 and will be clipped to those extremes. The value to minimize becomes: \(ER_{cost} = cost * FAR + (1-cost) * FRR\). The higher the cost, the higher the importance given to not making mistakes classifying negatives/noise/impostors.

Note

The scores will be sorted internally, requiring the scores to be copied. To avoid this copy, you can sort both sets of scores externally in ascendant order, and set the is_sorted parameter to True

Parameters:

negatives, positives : array_like(1D, float)

The set of negative and positive scores to compute the threshold

cost : float

The relative cost over FAR with respect to FRR in the threshold calculation

is_sorted : bool

[Default: False] Are both sets of scores already in ascendantly sorted order?

Returns:

threshold : float

The threshold for which the weighted error rate is minimal

bob.measure.ppndf(value) → ppndf¶

Returns the Deviate Scale equivalent of a false rejection/acceptance ratio

The algorithm that calculates the deviate scale is based on function ppndf() from the NIST package DETware version 2.1, freely available on the internet. Please consult it for more details. By 20.04.2011, you could find such package here.

Parameters:

value : float

The value (usually FAR or FRR) for which the ppndf should be calculated

Returns:

ppndf : float

The derivative scale of the given value

bob.measure.precision_recall(negatives, positives, threshold) → precision, recall¶

Calculates the precision and recall (sensitiveness) values given negative and positive scores and a threshold

Precision and recall are computed as:

\[ \begin{align}\begin{aligned}\mathrm{precision} = \frac{tp}{tp + fp}\\\mathrm{recall} = \frac{tp}{tp + fn}\end{aligned}\end{align} \]

where \(tp\) are the true positives, \(fp\) are the false positives and \(fn\) are the false negatives.

positives holds the score information for samples that are labeled to belong to a certain class (a.k.a., ‘signal’ or ‘client’). negatives holds the score information for samples that are labeled not to belong to the class (a.k.a., ‘noise’ or ‘impostor’). For more precise details about how the method considers error rates, see bob.measure.farfrr().

Parameters:

negatives, positives : array_like(1D, float)

The set of negative and positive scores to compute the measurements

threshold : float

The threshold to compute the measures for

Returns:

precision : float

The precision value for the given negatives and positives

recall : float

The recall value for the given negatives and positives

bob.measure.precision_recall_curve(negatives, positives, n_points) → curve¶

Calculates the precision-recall curve given a set of positive and negative scores and a number of desired points

The points in which the curve is calculated are distributed uniformly in the range [min(negatives, positives), max(negatives, positives)]

Parameters:

negatives, positives : array_like(1D, float)

The set of negative and positive scores to compute the measurements

n_points : int

The number of thresholds for which precision and recall should be evaluated

Returns:

curve : array_like(2D, float)

2D array of floats that express the X (precision) and Y (recall)

coordinates

bob.measure.roc(negatives, positives, n_points) → curve¶

Calculates points of an Receiver Operating Characteristic (ROC)

Calculates the ROC curve given a set of negative and positive scores and a desired number of points.

Parameters:

negatives, positives : array_like(1D, float)

The negative and positive scores, for which the ROC curve should be calculated

n_points : int

The number of points, in which the ROC curve are calculated, which are distributed uniformly in the range [min(negatives, positives), max(negatives, positives)]

Returns:

curve : array_like(2D, float)

A two-dimensional array of doubles that express the X (FAR) and Y (FRR) coordinates in this order

bob.measure.roc_for_far(negatives, positives, far_list[, is_sorted]) → curve¶

Calculates the ROC curve for a given set of positive and negative scores and the FAR values, for which the FRR should be computed

Note

The scores will be sorted internally, requiring the scores to be copied. To avoid this copy, you can sort both sets of scores externally in ascendant order, and set the is_sorted parameter to True

Parameters:

negatives, positives : array_like(1D, float)

The set of negative and positive scores to compute the curve

far_list : array_like(1D, float)

A list of FAR values, for which the FRR values should be computed

is_sorted : bool

[Default: False] Set this to True if both sets of scores are already sorted in ascending order. If False, scores will be sorted internally, which will require more memory

Returns:

curve : array_like(2D, float)

The ROC curve, which holds a copy of the given FAR values in row 0, and the corresponding FRR values in row 1

bob.measure.rocch(negatives, positives) → curve¶

Calculates the ROC Convex Hull (ROCCH) curve given a set of positive and negative scores

Parameters:

negatives, positives : array_like(1D, float)

The set of negative and positive scores to compute the curve

Returns:

curve : array_like(2D, float)

The ROC curve, with the first row containing the FAR, and the second row containing the FRR

bob.measure.rocch2eer(pmiss_pfa) → threshold¶

Calculates the threshold that is as close as possible to the equal-error-rate (EER) given the input data

Todo

The parameter(s) ‘pmiss_pfa’ are used, but not documented.

Returns:

threshold : float

The computed threshold, at which the EER can be obtained

A set of utilities to load score files with different formats.

bob.measure.load.open_file(filename, mode='rt')[source]¶

Opens the given score file for reading.

Score files might be raw text files, or a tar-file including a single score file inside.

Parameters:	filename (`str`, `file-like`) – The name of the score file to open, or a file-like object open for reading. If a file name is given, the according file might be a raw text file or a (compressed) tar file containing a raw text file.
Returns:	A read-only file-like object as it would be returned by `open()`.
Return type:	`file-like`

bob.measure.load.four_column(filename)[source]¶

Loads a score set from a single file and yield its lines

Loads a score set from a single file and yield its lines (to avoid loading the score file at once into memory). This function verifies that all fields are correctly placed and contain valid fields. The score file must contain the following information in each line:

claimed_id real_id test_label score

Parameters:

filename (str, file-like) – The file object that will be opened with open_file() containing the scores.

Yields:

str – The claimed identity – the client name of the model that was used in the comparison

str: The real identity – the client name of the probe that was used in the comparison

str: A label of the probe – usually the probe file name, or the probe id

float: The result of the comparison of the model and the probe

bob.measure.load.split_four_column(filename)[source]¶

Loads a score set from a single file and splits the scores

Loads a score set from a single file and splits the scores between negatives and positives. The score file has to respect the 4 column format as defined in the method four_column().

This method avoids loading and allocating memory for the strings present in the file. We only keep the scores.

Parameters:	filename (`str`, `file-like`) – The file object that will be opened with `open_file()` containing the scores.
Returns:	negatives, 1D float array containing the list of scores, for which the `claimed_id` and the `real_id` are different (see `four_column()`) array: positives, 1D float array containing the list of scores, for which the `claimed_id` and the `real_id` are identical (see `four_column()`)
Return type:	array

bob.measure.load.cmc_four_column(filename)[source]¶

Loads scores to compute CMC curves from a file in four column format.

The four column file needs to be in the same format as described in four_column(), and the test_label (column 3) has to contain the test/probe file name or a probe id.

This function returns a list of tuples. For each probe file, the tuple consists of a list of negative scores and a list of positive scores. Usually, the list of positive scores should contain only one element, but more are allowed. The result of this function can directly be passed to, e.g., the bob.measure.cmc() function.

Parameters:	filename (`str`, `file-like`) – The file object that will be opened with `open_file()` containing the scores.
Returns:	A list of tuples, where each tuple contains the `negative` and `positive` scores for one probe of the database. Both `negatives` and `positives` can be either an 1D `numpy.ndarray` of type `float`, or `None`.
Return type:	`list`

bob.measure.load.five_column(filename)[source]¶

Loads a score set from a single file and yield its lines

Loads a score set from a single file and yield its lines (to avoid loading the score file at once into memory). This function verifies that all fields are correctly placed and contain valid fields. The score file must contain the following information in each line:

claimed_id model_label real_id test_label score

Parameters:

filename (str, file-like) – The file object that will be opened with open_file() containing the scores.

Yields:

str – The claimed identity – the client name of the model that was used in the comparison

str: A label for the model – usually the model file name, or the model id

str: The real identity – the client name of the probe that was used in the comparison

str: A label of the probe – usually the probe file name, or the probe id

float: The result of the comparison of the model and the probe

bob.measure.load.split_five_column(filename)[source]¶

Loads a score set from a single file and splits the scores

Loads a score set from a single file in five column format and splits the scores between negatives and positives. The score file has to respect the 5 column format as defined in the method five_column().

This method avoids loading and allocating memory for the strings present in the file. We only keep the scores.

Parameters:	filename (`str`, `file-like`) – The file object that will be opened with `open_file()` containing the scores.
Returns:	negatives, 1D float array containing the list of scores, for which the `claimed_id` and the `real_id` are different (see `four_column()`) array: positives, 1D float array containing the list of scores, for which the `claimed_id` and the `real_id` are identical (see `four_column()`)
Return type:	array

bob.measure.load.cmc_five_column(filename)[source]¶

Loads scores to compute CMC curves from a file in five column format.

The five column file needs to be in the same format as described in five_column(), and the test_label (column 4) has to contain the test/probe file name or a probe id.

This function returns a list of tuples. For each probe file, the tuple consists of a list of negative scores and a list of positive scores. Usually, the list of positive scores should contain only one element, but more are allowed. The result of this function can directly be passed to, e.g., the bob.measure.cmc() function.

Parameters:	filename (`str`, `file-like`) – The file object that will be opened with `open_file()` containing the scores.
Returns:	A list of tuples, where each tuple contains the `negative` and `positive` scores for one probe of the database.
Return type:	`list`

bob.measure.load.scores(filename, ncolumns=None) → tuple[source]¶

Loads the scores from the given score file and yield its lines. Depending on the score file format, four or five elements are yielded, see bob.measure.load.four_column() and bob.measure.load.five_column() for details.

Parameters:

filename: str, file-like:: The file object that will be opened with open_file() containing the scores.
ncolumns: any: ignored

Yields:

tuple:: see bob.measure.load.four_column() or bob.measure.load.five_column()

bob.measure.load.split(filename, ncolumns=None) → negatives, positives[source]¶

Loads the scores from the given score file and splits them into positives and negatives.

Depending on the score file format, it calls see bob.measure.load.split_four_column() and :py:func:`bob.measure.load.split_five_column for details.

Parameters:

filename: str, file-like:: The file object that will be opened with open_file() containing the scores.
ncolumns: int or None: If specified to be 4 or 5, the score file will be assumed to be in the given format. If not specified, the score file format will be estimated automatically

Returns:

negatives: 1D numpy.ndarray of type float: This array contains the list of scores, for which the claimed_id and the real_id are different (see four_column())
positives: 1D numpy.ndarray of type float: This array contains the list of scores, for which the claimed_id and the real_id are identical (see four_column())

bob.measure.load.cmc(filename, ncolumns=None) → list[source]¶

Loads scores to compute CMC curves.

Depending on the score file format, it calls see bob.measure.load.cmc_four_column() and :py:func:`bob.measure.load.cmc_five_column for details.

Parameters:	filename (`str` or `file-like`) – The file object that will be opened with `open_file()` containing the scores. ncolumns – (`int`, Optional): If specified to be `4` or `5`, the score file will be assumed to be in the given format. If not specified, the score file format will be estimated automatically

Returns:

list: [(neg,pos)] A list of tuples, where each tuple contains the negative and positive scores for one probe of the database.

bob.measure.load.load_score(filename, ncolumns=None, minimal=False, **kwargs)[source]¶

Load scores using numpy.loadtxt and return the data as a numpy array.

Parameters:	filename (`str`, `file-like`) – The file object that will be opened with `open_file()` containing the scores. ncolumns (`int`, optional) – 4, 5 or None (the default), specifying the number of columns in the score file. If None is provided, the number of columns will be guessed. minimal (`bool`, optional) – If True, only loads `claimed_id`, `real_id`, and `scores`. **kwargs – Keyword arguments passed to `numpy.genfromtxt()`
Returns:	An array which contains not only the actual scores but also the `claimed_id`, `real_id`, `test_label` and `['model_label']`
Return type:	array

bob.measure.load.get_negatives_positives(score_lines)[source]¶: Take the output of load_score and return negatives and positives. This function aims to replace split_four_column and split_five_column but takes a different input. It’s up to you to use which one.

bob.measure.load.get_negatives_positives_from_file(filename, **kwargs)[source]¶: Loads the scores first efficiently and then calls get_negatives_positives

bob.measure.load.get_negatives_positives_all(score_lines_list)[source]¶: Take a list of outputs of load_score and return stacked negatives and positives.

bob.measure.load.get_all_scores(score_lines_list)[source]¶: Take a list of outputs of load_score and return stacked scores

bob.measure.load.dump_score(filename, score_lines)[source]¶: Dump scores that were loaded using load_score() The number of columns is automatically detected.

Measures for calibration

bob.measure.calibration.cllr(negatives, positives)[source]¶

Cost of log likelihood ratio as defined by the Bosaris toolkit

Computes the ‘cost of log likelihood ratio’ (\(C_{llr}\)) measure as given in the Bosaris toolkit

Parameters:	negatives (array) – 1D float array that contains the scores of the “negative” (noise, non-class) samples of your classifier. positives (array) – 1D float array that contains the scores of the “positive” (signal, class) samples of your classifier.
Returns:	The computed \(C_{llr}\) value.
Return type:	float

bob.measure.calibration.min_cllr(negatives, positives)[source]¶

Minimum cost of log likelihood ratio as defined by the Bosaris toolkit

Computes the ‘minimum cost of log likelihood ratio’ (\(C_{llr}^{min}\)) measure as given in the bosaris toolkit

Parameters:	negatives (array) – 1D float array that contains the scores of the “negative” (noise, non-class) samples of your classifier. positives (array) – 1D float array that contains the scores of the “positive” (signal, class) samples of your classifier.
Returns:	The computed \(C_{llr}^{min}\) value.
Return type:	float

bob.measure.plot.log_values(min_step=-4, counts_per_step=4)[source]¶

Computes log-scaled values between \(10^{M}\) and 1

This function computes log-scaled values between \(10^{M}\) and 1 (including), where \(M\) is the min_ste argument, which needs to be a negative integer. The integral counts_per_step value defines how many values between two adjacent powers of 10 will be created. The total number of values will be -min_step * counts_per_step + 1.

Parameters:	min_step (`int`, optional) – The power of 10 that will be the minimum value. E.g., the default `-4` will result in the first number to be \(10^{-4}\) = `0.00001` or `0.01%` counts_per_step (`int`, optional) – The number of values that will be put between two adjacent powers of 10. With the default value `4` (and default values of `min_step`), we will get `log_list[0] == 1e-4`, `log_list[4] == 1e-3`, …, `log_list[16] == 1`.
Returns:	A list of logarithmically scaled values between \(10^{M}\) and 1.
Return type:	`list`

bob.measure.plot.roc(negatives, positives, npoints=100, CAR=False, **kwargs)[source]¶

Plots Receiver Operating Characteristic (ROC) curve.

This method will call matplotlib to plot the ROC curve for a system which contains a particular set of negatives (impostors) and positives (clients) scores. We use the standard matplotlib.pyplot.plot() command. All parameters passed with exception of the three first parameters of this method will be directly passed to the plot command.

The plot will represent the false-alarm on the horizontal axis and the false-rejection on the vertical axis. The values for the axis will be computed using bob.measure.roc().

Note

This function does not initiate and save the figure instance, it only issues the plotting command. You are the responsible for setting up and saving the figure as you see fit.

Parameters:	negatives (array) – 1D float array that contains the scores of the “negative” (noise, non-class) samples of your classifier. See (`bob.measure.roc()`) positives (array) – 1D float array that contains the scores of the “positive” (signal, class) samples of your classifier. See (`bob.measure.roc()`) npoints (`int`, optional) – The number of points for the plot. See (`bob.measure.roc()`) CAR (`bool`, optional) – If set to `True`, it will plot the CAR over FAR in using `matplotlib.pyplot.semilogx()`, otherwise the FAR over FRR linearly using `matplotlib.pyplot.plot()`. kwargs (`dict`, optional) – Extra plotting parameters, which are passed directly to `matplotlib.pyplot.plot()`.
Returns:	The lines that were added as defined by the return value of `matplotlib.pyplot.plot()`.
Return type:	`list` of `matplotlib.lines.Line2D`

bob.measure.plot.roc_for_far(negatives, positives, far_values=[0.0001, 0.00017782794100389227, 0.00031622776601683794, 0.0005623413251903491, 0.001, 0.0017782794100389228, 0.0031622776601683794, 0.005623413251903491, 0.01, 0.01778279410038923, 0.03162277660168379, 0.05623413251903491, 0.1, 0.1778279410038923, 0.31622776601683794, 0.5623413251903491, 1.0], **kwargs)[source]¶

Plots the ROC curve for the given list of False Acceptance Rates (FAR).

This method will call matplotlib to plot the ROC curve for a system which contains a particular set of negatives (impostors) and positives (clients) scores. We use the standard matplotlib.pyplot.semilogx() command. All parameters passed with exception of the three first parameters of this method will be directly passed to the plot command.

The plot will represent the False Acceptance Rate (FAR) on the horizontal axis and the Correct Acceptance Rate (CAR) on the vertical axis. The values for the axis will be computed using bob.measure.roc_for_far().

Note

This function does not initiate and save the figure instance, it only issues the plotting command. You are the responsible for setting up and saving the figure as you see fit.

Parameters:	negatives (array) – 1D float array that contains the scores of the “negative” (noise, non-class) samples of your classifier. See (`bob.measure.roc()`) positives (array) – 1D float array that contains the scores of the “positive” (signal, class) samples of your classifier. See (`bob.measure.roc()`) far_values (`list`, optional) – The values for the FAR, where the CAR should be plotted; each value should be in range [0,1]. kwargs (`dict`, optional) – Extra plotting parameters, which are passed directly to `matplotlib.pyplot.plot()`.
Returns:	The lines that were added as defined by the return value of `matplotlib.pyplot.semilogx()`.
Return type:	`list` of `matplotlib.lines.Line2D`

bob.measure.plot.precision_recall_curve(negatives, positives, npoints=100, **kwargs)[source]¶

Plots a Precision-Recall curve.

This method will call matplotlib to plot the precision-recall curve for a system which contains a particular set of negatives (impostors) and positives (clients) scores. We use the standard matplotlib.pyplot.plot() command. All parameters passed with exception of the three first parameters of this method will be directly passed to the plot command.

Note

This function does not initiate and save the figure instance, it only issues the plotting command. You are the responsible for setting up and saving the figure as you see fit.

Parameters:	negatives (array) – 1D float array that contains the scores of the “negative” (noise, non-class) samples of your classifier. See (`bob.measure.precision_recall_curve()`) positives (array) – 1D float array that contains the scores of the “positive” (signal, class) samples of your classifier. See (`bob.measure.precision_recall_curve()`) npoints (`int`, optional) – The number of points for the plot. See (`bob.measure.precision_recall_curve()`) kwargs (`dict`, optional) – Extra plotting parameters, which are passed directly to `matplotlib.pyplot.plot()`.
Returns:	The lines that were added as defined by the return value of `matplotlib.pyplot.plot()`.
Return type:	`list` of `matplotlib.lines.Line2D`

bob.measure.plot.epc(dev_negatives, dev_positives, test_negatives, test_positives, npoints=100, **kwargs)[source]¶

Plots Expected Performance Curve (EPC) as defined in the paper:

Bengio, S., Keller, M., Mariéthoz, J. (2004). The Expected Performance Curve. International Conference on Machine Learning ICML Workshop on ROC Analysis in Machine Learning, 136(1), 1963–1966. IDIAP RR. Available: http://eprints.pascal-network.org/archive/00000670/

This method will call matplotlib to plot the EPC curve for a system which contains a particular set of negatives (impostors) and positives (clients) for both the development and test sets. We use the standard matplotlib.pyplot.plot() command. All parameters passed with exception of the five first parameters of this method will be directly passed to the plot command.

The plot will represent the minimum HTER on the vertical axis and the cost on the horizontal axis.

Note

This function does not initiate and save the figure instance, it only issues the plotting commands. You are the responsible for setting up and saving the figure as you see fit.

Parameters:	dev_negatives (array) – 1D float array that contains the scores of the “negative” (noise, non-class) samples of your classifier, from the development set. See (`bob.measure.epc()`) dev_positives (array) – 1D float array that contains the scores of the “positive” (signal, class) samples of your classifier, from the development set. See (`bob.measure.epc()`) test_negatives (array) – 1D float array that contains the scores of the “negative” (noise, non-class) samples of your classifier, from the test set. See (`bob.measure.epc()`) test_positives (array) – 1D float array that contains the scores of the “positive” (signal, class) samples of your classifier, from the test set. See (`bob.measure.epc()`) npoints (`int`, optional) – The number of points for the plot. See (`bob.measure.epc()`) kwargs (`dict`, optional) – Extra plotting parameters, which are passed directly to `matplotlib.pyplot.plot()`.
Returns:	The lines that were added as defined by the return value of `matplotlib.pyplot.plot()`.
Return type:	`list` of `matplotlib.lines.Line2D`

bob.measure.plot.det(negatives, positives, npoints=100, axisfontsize='x-small', **kwargs)[source]¶

Plots Detection Error Trade-off (DET) curve as defined in the paper:

Martin, A., Doddington, G., Kamm, T., Ordowski, M., & Przybocki, M. (1997). The DET curve in assessment of detection task performance. Fifth European Conference on Speech Communication and Technology (pp. 1895-1898). Available: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.117.4489&rep=rep1&type=pdf

This method will call matplotlib to plot the DET curve(s) for a system which contains a particular set of negatives (impostors) and positives (clients) scores. We use the standard matplotlib.pyplot.plot() command. All parameters passed with exception of the three first parameters of this method will be directly passed to the plot command.

The plot will represent the false-alarm on the horizontal axis and the false-rejection on the vertical axis.

This method is strongly inspired by the NIST implementation for Matlab, called DETware, version 2.1 and available for download at the NIST website:

http://www.itl.nist.gov/iad/mig/tools/

Note

This function does not initiate and save the figure instance, it only issues the plotting commands. You are the responsible for setting up and saving the figure as you see fit.

Note

If you wish to reset axis zooming, you must use the Gaussian scale rather than the visual marks showed at the plot, which are just there for displaying purposes. The real axis scale is based on bob.measure.ppndf(). For example, if you wish to set the x and y axis to display data between 1% and 40% here is the recipe:

import bob.measure
from matplotlib import pyplot
bob.measure.plot.det(...) #call this as many times as you need
#AFTER you plot the DET curve, just set the axis in this way:
pyplot.axis([bob.measure.ppndf(k/100.0) for k in (1, 40, 1, 40)])

We provide a convenient way for you to do the above in this module. So, optionally, you may use the bob.measure.plot.det_axis() method like this:

import bob.measure
bob.measure.plot.det(...)
# please note we convert percentage values in det_axis()
bob.measure.plot.det_axis([1, 40, 1, 40])

Parameters:	negatives (array) – 1D float array that contains the scores of the “negative” (noise, non-class) samples of your classifier. See (`bob.measure.det()`) positives (array) – 1D float array that contains the scores of the “positive” (signal, class) samples of your classifier. See (`bob.measure.det()`) npoints (`int`, optional) – The number of points for the plot. See (`bob.measure.det()`) axisfontsize (`str`, optional) – The size to be used by x/y-tick-labels to set the font size on the axis kwargs (`dict`, optional) – Extra plotting parameters, which are passed directly to `matplotlib.pyplot.plot()`.
Returns:	The lines that were added as defined by the return value of `matplotlib.pyplot.plot()`.
Return type:	`list` of `matplotlib.lines.Line2D`

bob.measure.plot.det_axis(v, **kwargs)[source]¶

Sets the axis in a DET plot.

This method wraps the matplotlib.pyplot.axis() by calling bob.measure.ppndf() on the values passed by the user so they are meaningful in a DET plot as performed by bob.measure.plot.det().

Parameters:	v (`sequence`) – A sequence (list, tuple, array or the like) containing the X and Y limits in the order `(xmin, xmax, ymin, ymax)`. Expected values should be in percentage (between 0 and 100%). If `v` is not a list or tuple that contains 4 numbers it is passed without further inspection to `matplotlib.pyplot.axis()`. kwargs (`dict`, optional) – Extra plotting parameters, which are passed directly to `matplotlib.pyplot.axis()`.
Returns:	Whatever is returned by `matplotlib.pyplot.axis()`.
Return type:	object

bob.measure.plot.cmc(cmc_scores, logx=True, **kwargs)[source]¶

Plots the (cumulative) match characteristics and returns the maximum rank.

This function plots a CMC curve using the given CMC scores, which can be read from the our score files using the bob.measure.load.cmc_four_column() or bob.measure.load.cmc_five_column() methods. The structure of the cmc_scores parameter is relatively complex. It contains a list of pairs of lists. For each probe object, a pair of list negative and positive scores is required.

Parameters:	cmc_scores (array) – 1D float array containing the CMC values (See `bob.measure.cmc()`) logx (`bool`, optional) – If set (the default), plots the rank axis in logarithmic scale using `matplotlib.pyplot.semilogx()` or in linear scale using `matplotlib.pyplot.plot()` kwargs (`dict`, optional) – Extra plotting parameters, which are passed directly to `matplotlib.pyplot.plot()`.
Returns:	The number of classes (clients) in the given scores.
Return type:	int

bob.measure.plot.detection_identification_curve(cmc_scores, far_values=[0.0001, 0.00017782794100389227, 0.00031622776601683794, 0.0005623413251903491, 0.001, 0.0017782794100389228, 0.0031622776601683794, 0.005623413251903491, 0.01, 0.01778279410038923, 0.03162277660168379, 0.05623413251903491, 0.1, 0.1778279410038923, 0.31622776601683794, 0.5623413251903491, 1.0], rank=1, logx=True, **kwargs)[source]¶

Plots the Detection & Identification curve over the FAR

This curve is designed to be used in an open set identification protocol, and defined in Chapter 14.1 of [LiJain2005]. It requires to have at least one open set probe item, i.e., with no corresponding gallery, such that the positives for that pair are None.

The detection and identification curve first computes FAR thresholds based on the out-of-set probe scores (negative scores). For each probe item, the maximum negative score is used. Then, it plots the detection and identification rates for those thresholds, which are based on the in-set probe scores only. See [LiJain2005] for more details.

[LiJain2005]

(1, 2, 3, 4) Stan Li and Anil K. Jain, Handbook of Face Recognition, Springer, 2005

Parameters:	cmc_scores (array) – 1D float array containing the CMC values (See `bob.measure.cmc()`) rank (`int`, optional) – The rank for which the curve should be plotted far_values (`list`, optional) – The values for the FAR, where the CAR should be plotted; each value should be in range [0,1]. logx (`bool`, optional) – If set (the default), plots the rank axis in logarithmic scale using `matplotlib.pyplot.semilogx()` or in linear scale using `matplotlib.pyplot.plot()` kwargs (`dict`, optional) – Extra plotting parameters, which are passed directly to `matplotlib.pyplot.plot()`.
Returns:	The lines that were added as defined by the return value of `matplotlib.pyplot.plot()`.
Return type:	`list` of `matplotlib.lines.Line2D`

This file includes functionality to convert between Bob’s four column or five column score files and the Matrix files used in OpenBR.

bob.measure.openbr.write_matrix(score_file, matrix_file, mask_file, model_names=None, probe_names=None, score_file_format='4column', gallery_file_name='unknown-gallery.lst', probe_file_name='unknown-probe.lst', search=None)[source]¶

Writes the OpenBR matrix and mask files (version 2), given a score file.

If gallery and probe names are provided, the matrices in both files will be sorted by gallery and probe names. Otherwise, the order will be the same as given in the score file.

If search is given (as an integer), the resulting matrix files will be in the search format, keeping the given number of gallery scores with the highest values for each probe.

Warning

When provided with a 4-column score file, this function will work only, if there is only a single model id for each client.

Parameters:

score_file (str) – The 4 or 5 column style score file written by bob.
matrix_file (str) – The OpenBR matrix file that should be written. Usually, the file name extension is .mtx
mask_file (str) – The OpenBR mask file that should be written. The mask file defines, which values are positives, negatives or to be ignored. Usually, the file name extension is .mask
model_names (str, optional) –
If given, the matrix will be written in the same order as the given model names. The model names must be identical with the second column in the 5-column score_file.

Note

If the score file is in four column format, the model_names must be the client ids stored in the first column. In this case, there might be only a single model per client

Only the scores of the given models will be considered.
probe_names (list, optional) – A list of strings. If given, the matrix will be written in the same order as the given probe names (the path of the probe). The probe names are identical to the third column of the 4-column (or the fourth column of the 5-column) score_file. Only the scores of the given probe names will be considered in this case.
score_file_format (str, optional) – One of ('4column', '5column'). The format, in which the score_file is; defaults to '4column'
gallery_file_name (str, optional) – The name of the gallery file that will be written in the header of the OpenBR files.
probe_file_name (str, optional) – The name of the probe file that will be written in the header of the OpenBR files.
search (int, optional) – If given, the scores will be sorted per probe, keeping the specified number of highest scores. If the given number is higher than the models, NaN values will be added, and the mask will contain 0x00 values.

bob.measure.openbr.write_score_file(matrix_file, mask_file, score_file, models_ids=None, probes_ids=None, model_names=None, probe_names=None, score_file_format='4column', replace_nan=None)[source]¶

Writes the Bob score file in the desired format from OpenBR files.

Writes a Bob score file in the desired format (four or five column), given the OpenBR matrix and mask files.

In principle, the score file can be written based on the matrix and mask files, and the format suffice the requirements to compute CMC curves. However, the contents of the score files can be adapted. If given, the models_ids and probes_ids define the client ids of model and probe, and they have to be in the same order as used to compute the OpenBR matrix. The model_names and probe_names define the paths of model and probe, and they should be in the same order as the ids.

In rare cases, the OpenBR matrix contains NaN values, which Bob’s score files cannot handle. You can use the replace_nan parameter to decide, what to do with these values. By default (None), these values are ignored, i.e., not written into the score file. This is, what OpenBR is doing as well. However, you can also set replace_nan to any value, which will be written instead of the NaN values.

Parameters:

matrix_file (str) – The OpenBR matrix file that should be read. Usually, the file name extension is .mtx
mask_file (str) – The OpenBR mask file that should be read. Usually, the file name extension is .mask
score_file (str) – Path to the 4 or 5 column style score file that should be written.
models_ids (list, optional) – A list of strings with the client ids of the models that will be written in the first column of the score file. If given, the size must be identical to the number of models (gallery templates) in the OpenBR files. If not given, client ids of the model will be identical to the gallery index in the matrix file.
probes_ids (list, optional) – A list of strings with the client ids of the probes that will be written in the second/third column of the four/five column score file. If given, the size must be identical to the number of probe templates in the OpenBR files. It will be checked that the OpenBR mask fits to the model/probe client ids. If not given, the probe ids will be estimated automatically, i.e., to fit the OpenBR matrix.
model_names (list, optional) –
A list of strings with the model path written in the second column of the five column score file. If not given, the model index in the OpenBR file will be used.

Note

This entry is ignored in the four column score file format.
probe_names (list, optional) – A list of probe path to be written in the third/fourth column in the four/five column score file. If given, the size must be identical to the number of probe templates in the OpenBR files. If not given, the probe index in the OpenBR file will be used.
score_file_format (str, optional) – One of ('4column', '5column'). The format, in which the score_file is; defaults to '4column'
replace_nan (float, optional) – If NaN values are encountered in the OpenBR matrix (which are not ignored due to the mask being non-NULL), this value will be written instead. If None, the values will not be written in the score file at all.