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What would you like to do?
Generate matrix plot for confusion matrix with pretty annotations.
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns
from sklearn.metrics import confusion_matrix
def cm_analysis(y_true, y_pred, filename, labels, ymap=None, figsize=(10,10)):
Generate matrix plot of confusion matrix with pretty annotations.
The plot image is saved to disk.
y_true: true label of the data, with shape (nsamples,)
y_pred: prediction of the data, with shape (nsamples,)
filename: filename of figure file to save
labels: string array, name the order of class labels in the confusion matrix.
use `clf.classes_` if using scikit-learn models.
with shape (nclass,).
ymap: dict: any -> string, length == nclass.
if not None, map the labels & ys to more understandable strings.
Caution: original y_true, y_pred and labels must align.
figsize: the size of the figure plotted.
if ymap is not None:
y_pred = [ymap[yi] for yi in y_pred]
y_true = [ymap[yi] for yi in y_true]
labels = [ymap[yi] for yi in labels]
cm = confusion_matrix(y_true, y_pred, labels=labels)
cm_sum = np.sum(cm, axis=1, keepdims=True)
cm_perc = cm / cm_sum.astype(float) * 100
annot = np.empty_like(cm).astype(str)
nrows, ncols = cm.shape
for i in range(nrows):
for j in range(ncols):
c = cm[i, j]
p = cm_perc[i, j]
if i == j:
s = cm_sum[i]
annot[i, j] = '%.1f%%\n%d/%d' % (p, c, s)
elif c == 0:
annot[i, j] = ''
annot[i, j] = '%.1f%%\n%d' % (p, c)
cm = pd.DataFrame(cm, index=labels, columns=labels) = 'Actual' = 'Predicted'
fig, ax = plt.subplots(figsize=figsize)
sns.heatmap(cm, annot=annot, fmt='', ax=ax)
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koursera commented Nov 3, 2020

Do you mean the order of 0 and 1?

Yes, I was looking to align this with sklearn's confusion matrix for consistency. Perhaps a parameter could be passed to indicate the order since various references have a different convention for the axes.

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hitvoice commented Nov 4, 2020

You can see from the code that the matrix is indeed computed from sklearn's "confusion_matrix" function. How did you get the first figure? If you prefer that kind of style, you can reorder the dataframe columns by cm = cm[cm.columns[::-1]] before creating the plot.

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kalkite commented Oct 11, 2021

@hitvoice, it's really appreciated work. how to changet the clf.classes_ to other, for instance my classess are from 0 to 8, but i want to change those labels to string.

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@rajeshkalakoti pass the value of ymap (dict[Any,str]) to cm_analysis. You can configure the class names in ymap.

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kalkite commented Oct 24, 2021

for instance, labels are like "class-1, class-2,class-3, class-4,class-5, class-6,class-7, class-8,classs-9", how to configure it?

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