How to change the least count of axis in mathplotlib

Question

I have the following script to generate a heatmap of NxN cores :

import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
import numpy as np

matrix = np.random.randint(300,high=400, size=(4, 4))

heatmap = plt.pcolor(np.array(matrix))

for y in range(len(matrix)):
    for x in range(len(matrix[0])):
        plt.text(x + 0.5, y + 0.5, '%.4f' % matrix[y][x],
                 horizontalalignment='center',
                 verticalalignment='center',
                 )

plt.colorbar(heatmap)
plt.xlabel ("Cores")
plt.ylabel ("Cores")
plt.title ("Temperature Map of the NxN Cores")
plt.savefig ("xyz"+".png")
plt.show()
plt.clf()

It produces this :

As each of squares depict a core, the values of 0.5, 1.5 etc. don't make any sense.

I want the axis values to be integers only. I looked up the docs for this but could not find a way to achieve this.

RonD · Accepted Answer · 2016-11-30 07:03:36Z

1

You can explicitly set where you want to tick marks with plt.xticks and plt.yticks.

For your example:

plt.xticks(range(min(x), max(x)+1))
plt.yticks(range(min(y), max(y)+1))
plt.show()

If your data in not integers, you could use:

import numpy as np
plt.xticks(np.arange(min(x), max(x)+1, 1.0))
plt.yticks(np.arange(min(y), max(y)+1, 1.0))
plt.show()

answered Nov 30, 2016 at 7:03

RonD

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3 Comments

Rohith R Over a year ago

That works. I t would be nice to include where you find such information, so that others may also use the source.

RonD Over a year ago

I knew it because I found it previously in stack overflow.

RonD Over a year ago

But here is the formal page: matplotlib.org/api/…

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