CODEWITHSUNDEEP
pythonnumpymatplotlib
code base 5000
code base 5000

Reputation: 4102

Assign Specific Values to Matplotlib graph

I have two values in a numpy array. 0,1. I want to ensure 1 is always black and 0 is always grey when I graph the array.

How can I do this in matplotlib?

Thank you

Upvotes: 0

Views: 42

Answers (1)

ImportanceOfBeingErnest
ImportanceOfBeingErnest

Reputation: 339230

Assuming that you want to plot an image plot (plt.imshow()), you can select a colormap like "gray_r" which has white as lowest and black as highest color, gray will be in the middle. If you now normalize the image plot to values between -1 and 1, the array's 0 value will correspond to the middle of the colormap (being gray) and 1 will correspond to the upper end of the colormap (being black).

import matplotlib.pyplot as plt
import numpy as np; np.random.seed(0)

a = np.random.randint(0,2, size=(12,25))

plt.imshow(a, cmap="gray_r", vmin=-1, vmax=1)

plt.show()

enter image description here

Upvotes: 3

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