Commit 3e3792ed authored by Rakesh MEHTA's avatar Rakesh MEHTA
Browse files

Confusion matrix util modified

parent 55f0635f
import numpy
import matplotlib.pyplot
def confusion_matrix(expected, predicted):
"""Transforms the prediction list into a confusion matrix
This method takes lists of expected and predicted classes and returns a
confusion matrix, which represents the percentage of classified examples in
each combination of "expected class" of samples and "predicated class" of the
same samples.
Keyword parameters:
expected (numpy.ndarray, 1D)
The ground-thruth
predicted (numpy.ndarray, 1D)
The predicted classes with your neural network
You must combine these scores column wise and determine what are the
annotated rates (below) for each of the column entries, returning the
following 2D numpy.ndarray::
[ TP0 / N0 FP1(0) / N1 FP2(0) / N2 ... ]
[ FP0(1) / N0 TP1 / N1 FP2(1) / N2 ... ]
[ FP0(2) / N0 FP1(2) / N1 TP2 / N2 ... ]
[ ... ... ... ]
[ FP0(9) / N0 FP1(9) / N1 TP9 / N9 ... ]
Where:
TPx / Nx
True Positive Rate for class ``x``
FPx(y) / Nz
Rate of False Positives for class ``y``, from class ``x``. That is,
elements from class ``x`` that have been **incorrectly** classified as
``y``.
"""
retval = numpy.zeros((10,10), dtype=float)
for k in range(10):
pred_k = predicted[expected==k] # predictions that are supposed to be 'k'
retval[:,k] = numpy.array([len(pred_k[pred_k==p]) for p in range(10)])
retval[:,k] /= len(pred_k)
return retval
def display_cm(cm, title_str = "Confusion Matrix"):
......
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