Metrics

Compute metrics for assessing the performance of classification/regression models.

Classification

Examples:

>>> import mlpy
>>> t = [3,2,3,3,3,1,1,1]
>>> p = [3,2,1,3,3,2,1,1]
>>> mlpy.error(t, p)
0.25
>>> mlpy.accuracy(t, p)
0.75

Binary Classification Only

The Confusion Matrix:

Total Samples (ts)

Actual Positives (ap)

Actual Negatives (an)

Predicted Positives (pp)

True Positives (tp)

False Positives (fp)

Predicted Negatives (pn)

False Negatives (fn)

True Negatives (tn)

Examples:

>>> import mlpy
>>> t = [1, 1, 1,-1, 1,-1,-1,-1]
>>> p = [1,-1, 1, 1, 1,-1, 1,-1]
>>> mlpy.error_p(t, p)
0.25
>>> mlpy.error_n(t, p)
0.5
>>> mlpy.sensitivity(t, p)
0.75
>>> mlpy.specificity(t, p)
0.5
>>> mlpy.ppv(t, p)
0.59999999999999998
>>> mlpy.npv(t, p)
0.66666666666666663
>>> mlpy.mcc(t, p)
0.2581988897471611
>>> p = [2.3,-0.4, 1.6, 0.6, 3.2,-4.9, 1.3,-0.3]
>>> mlpy.auc_wmw(t, p)
0.8125
>>> p = [2.3,0.4, 1.6, -0.6, 3.2,-4.9, -1.3,-0.3]
>>> mlpy.auc_wmw(t, p)
1.0

Regression

Example:

>>> import mlpy
>>> t = [2.4,0.4,1.2,-0.2,3.3,-4.9,-1.1,-0.1]
>>> p = [2.3,0.4,1.6,-0.6,3.2,-4.9,-1.3,-0.3]
>>> mlpy.mse(t, p)
0.052499999999999998