How to create image of confusion matrix in Python

Question

I am new to Python and Machine Learning. I am working about multi-class classification (3 classes). I want to save confusion matrix as an image. Now, sklearn.metrics.confusion_matrix() helps me to find the confusion matrix like:

array([[35, 0, 6],
   [0, 0, 3],
   [5, 50, 1]])

Next, I would like to know how to convert this confusion matrix to become image and save as png.

Answer 1

OPTION 1:

After you get array of the confusion matrix from sklearn.metrics, you can use matplotlib.pyplot.matshow() or seaborn.heatmap to generate the plot of the confusion matrix from that array.

e.g.

import pandas as pd
import seaborn as sn
import matplotlib.pyplot as plt

cfm = [[35, 0, 6],
       [0, 0, 3],
       [5, 50, 1]]
classes = ["0", "1", "2"]

df_cfm = pd.DataFrame(cfm, index = classes, columns = classes)
plt.figure(figsize = (10,7))
cfm_plot = sn.heatmap(df_cfm, annot=True)
cfm_plot.figure.savefig("cfm.png")

---

OPTION 2:

You can use plot_confusion_matrix() from sklearn to create image of confusion matrix directly from an estimater (i.e. classifier).

e.g.

cfm_plot = plot_confusion_matrix(<estimator>, <X>, <Y>)
cfm_plot.savefig("cfm.png")

Both options use savefig() to save the result as the png file.

REF: https://scikit-learn.org/stable/modules/generated/sklearn.metrics.plot_confusion_matrix.html