CODEWITHSUNDEEP
pythonmatplotlibjupyter-notebook
Partha S Satpathy
Partha S Satpathy

Reputation: 11

Jupyter notebook displays matplotlib pcolor image in grey-scale instead of color

I am running the below code to display the Z function. The output is supposed to come in color. However, it is displaying in grey-scale. This is in Jupyter notebook. It is showing in color when I run in other places.

# Import numpy and matplotlib.pyplot
import numpy as np
import matplotlib.pyplot as plt

# Generate two 1-D arrays: u, v
u = np.linspace(-2, 2, 41)
v = np.linspace(-1,1,21)

# Generate 2-D arrays from u and v: X, Y
X,Y = np.meshgrid(u,v)

# Compute Z based on X and Y
Z = np.sin(3*np.sqrt(X**2 + Y**2)) 

# Display the resulting image with pcolor()
plt.pcolor(Z)
plt.show()

Upvotes: 1

Views: 1602

Answers (2)

gereleth
gereleth

Reputation: 2482

Besides setting the default colormap you can pass one directly to the pcolor method:

from matplotlib import cm
plt.pcolor(Z, cmap = cm.viridis)

In a Jupyter notebook you can press TAB after typing cm. to see all available colormaps.

Upvotes: 2

Partha S Satpathy
Partha S Satpathy

Reputation: 11

I found that this is because the default color-map is 'Greys' for me. plt.rcParams['image.cmap']

results in 'Greys'.

I can set it to 'jet' which now shows the plots in color. 

plt.rcParams['image.cmap'] = 'jet'

Upvotes: 0

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