What is use of Heat map ? How to plot heat map?

A heat map is a data visualization technique that shows magnitude of a phenomenon as color in two dimensions. The variation in color may be by hue or intensity, giving obvious visual cues to the reader about how the phenomenon is clustered or varies over space.

There are two fundamentally different categories of heat maps:

1. The cluster heat map
2.  The spatial heat map.

Plot heat map

import seaborn as sns
sns.heatmap(num_data.corr(), annot=True)