nltk.ConfusionMatrix

class nltk.ConfusionMatrix(reference, test, sort_by_count=False)[source]

The confusion matrix between a list of reference values and a corresponding list of test values. Entry [r,t] of this matrix is a count of the number of times that the reference value r corresponds to the test value t. E.g.:

>>> from nltk.metrics import ConfusionMatrix
>>> ref  = 'DET NN VB DET JJ NN NN IN DET NN'.split()
>>> test = 'DET VB VB DET NN NN NN IN DET NN'.split()
>>> cm = ConfusionMatrix(ref, test)
>>> print(cm['NN', 'NN'])
3

Note that the diagonal entries Ri=Tj of this matrix corresponds to correct values; and the off-diagonal entries correspond to incorrect values.

Methods

__init__(reference, test[, sort_by_count]) Construct a new confusion matrix from a list of reference values and a corresponding list of test values.
key()
pretty_format([show_percents, ...])
return:A multi-line string representation of this confusion matrix.
unicode_repr()