Introduction

In this tutorial, we want to have a look at some Colormaps provided by Matplotlib and use them in a Scatterplot.

Import Libraries

First, we import the Pyplot submodule. The Pyplot submodule contains a collection of important functions such as the plot() function or the scatter() function. In addition, we import NumPy.

import matplotlib.pyplot as plt
import numpy as np

Define Data

Now, let's define some example data points. In order to do this, we create the following NumPy Arrays:

x = np.array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
y = np.array([4, 17, 10, 16, 18, 2, 7, 19, 15, 8])

Colormaps

Colormaps define a specific color range. The following colorbar visualizes an example of a Colormap. This Colormap ranges from 1 to 10.

Matplotlib offers a wide selection of Colormaps. These Colormaps differ in the colors and in the transition between the colors.

Use Colormap in Scatter Plot

Now, let's try different Colormaps. In order to do this, we create a Scatterplot and set the c and the cmap parameter.

The c parameter is the color range. The color range must be defined.

The cmap parameter is the Colormap. Here we can choose the name of a Colormap provided by Matplotlib. By changing value of the cmap parameter we can use different Colormaps.

Set Color Range

First, we need to set the color range of our Colormap. In our case, we choose a range from 1 to 10.

colors = np.arange(1, 11, 1)

Colormap: Magma

Let's create a Scatterplot with the colormap "magma".

colors = np.arange(1, 11, 1)

plt.scatter(x, y, c=colors, cmap='magma')
plt.colorbar()
plt.show()

Colormap: Viridis

Let's create a Scatterplot with the colormap "viridis".

plt.scatter(x, y, c=colors, cmap='viridis')
plt.colorbar()
plt.show()

Colormap: Plasma

Let's create a Scatterplot with the colormap "plasma".

plt.scatter(x, y, c=colors, cmap='plasma')
plt.colorbar()
plt.show()

Colormap: Inferno

Let's create a Scatterplot with the colormap "inferno".

plt.scatter(x, y, c=colors, cmap='inferno')
plt.colorbar()
plt.show()

Colormap: Cividis

Let's create a Scatterplot with the colormap "cividis".

plt.scatter(x, y, c=colors, cmap='cividis')
plt.colorbar()
plt.show()

Overview of Colormaps

Finally, we an overview of the Colormaps:

#plot 1 - magma
plt.subplot(2, 3, 1)
plt.scatter(x, y, c=colors, cmap='magma')
plt.colorbar()
plt.title('magma')

#plot 2 - viridis
plt.subplot(2, 3, 2)
plt.scatter(x, y, c=colors, cmap='viridis')
plt.colorbar()
plt.title('viridis')

#plot 3 - plasma
plt.subplot(2, 3, 3)
plt.scatter(x, y, c=colors, cmap='plasma')
plt.colorbar()
plt.title('plasma')

#plot 4 - inferno
plt.subplot(2, 3, 4)
plt.scatter(x, y, c=colors, cmap='inferno')
plt.colorbar()
plt.title('inferno')

#plot 5 - cividis
plt.subplot(2, 3, 5)
plt.scatter(x, y, c=colors, cmap='cividis')
plt.colorbar()
plt.title('cividis')

plt.tight_layout()
plt.show()

Conclusion

Congratulations! Now you are one step closer to become an AI Expert. You have seen that it is very easy to use Colormaps provided by Matplotlib. Try it yourself!

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