nltk.metrics.confusionmatrix.ConfusionMatrix

class documentation

class ConfusionMatrix(object): (source)

Constructor: ConfusionMatrix(reference, test, sort_by_count)

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.

Method	`__getitem__`	value `lj` was given. :rtype: int
Method	`__init__`	Construct a new confusion matrix from a list of reference values and a corresponding list of test values.
Method	`__repr__`	Undocumented
Method	`__str__`	Undocumented
Method	`key`	Undocumented
Method	`pretty_format`	@todo: add marginals?
Instance Variable	`_confusion`	Undocumented
Instance Variable	`_correct`	Undocumented
Instance Variable	`_indices`	Undocumented
Instance Variable	`_max_conf`	Undocumented
Instance Variable	`_total`	Undocumented
Instance Variable	`_values`	Undocumented

def __getitem__(self, li_lj_tuple): (source) ¶

value lj was given. :rtype: int

Returns
The number of times that value `li` was expected and

def __init__(self, reference, test, sort_by_count=False): (source) ¶

Construct a new confusion matrix from a list of reference values and a corresponding list of test values.

Parameters
reference:list	An ordered list of reference values.
test:list	A list of values to compare against the corresponding reference values.
sort_by_count	Undocumented
Raises
`ValueError`	If `reference` and `length` do not have the same length.

def __repr__(self): (source) ¶

Undocumented

def __str__(self): (source) ¶

Undocumented

def key(self): (source) ¶

Undocumented

def pretty_format(self, show_percents=False, values_in_chart=True, truncate=None, sort_by_count=False): (source) ¶

@todo: add marginals?

Parameters
show_percents	Undocumented
values_in_chart	Undocumented
truncate:int	If specified, then only show the specified number of values. Any sorting (e.g., sort_by_count) will be performed before truncation.
sort_by_count	If true, then sort by the count of each label in the reference data. I.e., labels that occur more frequently in the reference label will be towards the left edge of the matrix, and labels that occur less frequently will be towards the right edge.
Returns
A multi-line string representation of this confusion matrix.

_confusion = (source) ¶

Undocumented

_correct = (source) ¶

Undocumented

_indices = (source) ¶

Undocumented

_max_conf = (source) ¶

Undocumented

_total = (source) ¶

Undocumented

_values = (source) ¶

Undocumented