Updating aesthetics of matplotlib heatmap

Question

import matplotlib.pyplot as plt
import numpy as np
column_labels = list('ABCD')
row_labels = list('WXYZ')
data = np.random.rand(4,4)
fig, ax = plt.subplots()
heatmap = ax.pcolor(data, cmap=plt.cm.Blues)

# put the major ticks at the middle of each cell
ax.set_xticks(np.arange(data.shape[0])+0.5, minor=False)
ax.set_yticks(np.arange(data.shape[1])+0.5, minor=False)

# want a more natural, table-like display
ax.invert_yaxis()
ax.xaxis.set_label_position('top') # <-- This doesn't work!

ax.set_xticklabels(row_labels, minor=False)
ax.set_yticklabels(column_labels, minor=False)
plt.show()

Above code is from: Moving x-axis to the top of a plot in matplotlib

How can I change output from this script so that it looks aesthetically more like this picture:

Any solution using python matplotlib or seaborn works. I want to insert white between the cells, have the cells be square and also control their size

Asked By: user308827

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Source

Answer 1

I think you need 2 tricks. First, add the line

ax.set_aspect('equal')

to make the cells appear as squares (assuming that you have an equal number on the x- and y-axes, as in your example). If you have x squares on the x-axis and y squares on the y-axis, I suspect that you could instead do,

ax.set_aspect(float(y) / float(x))

Second, you need to add edgecolor to the cells and make the edges thick, so modify your line to e.g.,

heatmap = ax.pcolor(data, cmap=plt.cm.Blues, edgecolor='white', linewidths=10)

The result is

Answered By: innisfree

Answer 2

Following the tutorial of matplotlib, you can add extra minor ticks on the axes and apply a white grid on those minor ticks. It causes a padding effect on your heatmap like plot

# Turn spines off and create white grid.
ax.spines[:].set_visible(False)
ax.set_xticks(np.arange(data.shape[1]+1)-.5, minor=True)
ax.set_yticks(np.arange(data.shape[0]+1)-.5, minor=True)
ax.grid(which="minor", color="w", linestyle='-', linewidth=3) # change the appearance of your padding here
ax.tick_params(which="minor", bottom=False, left=False)

Answered By: alierdogan7

Updating aesthetics of matplotlib heatmap

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