[Python] Show labels on maps in Seaborn heatmap

Overview

When creating a heatmap with seaborn, you may want to display a label on the map.

This time, I will introduce such a method.

Method

When displaying the value as it is that creates the heatmap

If you set annot = True, you can display the value of the data passed to the argument of heatmap on the map.

import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns

x=np.random.randint(0, 10, (8, 8))

fig, ax=plt.subplots()
ax=sns.heatmap(x, annot=True)
plt.show()

When displaying a label different from the value that creates the heatmap

You may want to display a label different from the data that creates the heatmap.

For example, for each number, 1 is displayed if a certain condition is met, 0 is displayed if it is not met, and so on.

In such a case, you can pass an array of the same size as the data to annot.

y=np.zeros(x.shape)

for i in range(x.shape[0]):
    for j in range(x.shape[1]):
        if x[i][j]%2==0:
            y[i][j]=1   //If x is even, y is 1.           

//omit
ax=sns.heatmap(x, annot=y)
//omit