Visualizing heat maps

Let's look at how to visualize heat maps in this recipe. This is a pictorial representation of data where two groups are associated point by point. The individual values that are contained in a matrix are represented as color values in the plot.

How to do it…

1. Create a new Python file, and import the following packages:

   import numpy as np
   import matplotlib.pyplot as plt

2. Define the two groups:

   # Define the two groups 
   group1 = ['France', 'Italy', 'Spain', 'Portugal', 'Germany'] 
   group2 = ['Japan', 'China', 'Brazil', 'Russia', 'Australia']

3. Generate a random 2D matrix:

   # Generate some random values
   data = np.random.rand(5, 5)

4. Create a figure:

   # Create a figure
   fig, ax = plt.subplots()

5. Create the heat map:

   # Create the heat map
   heatmap = ax.pcolor(data, cmap=plt.cm.gray)

6. Plot these values:

   # Add major ticks at the middle of each cell
   ax.set_xticks(np.arange(data.shape[0])...