A colorbar is a bar that runs along the side of a Matplotlib chart and acts as a legend for the colors shown in the chart.
Matplotlib displays colorbars on the right side of a chart by default, but you can easily change this by using functions from the Matplotlib AxesGrid toolkit.
This tutorial shows several examples of how to use these functions in practice.
Example 1: Position Colorbar on Right Side of Chart
The following code shows how to generate a Matplotlib chart and how to place a colorbar on the right side of the chart:
import numpy as np import matplotlib.pyplot as plt from mpl_toolkits.axes_grid1 import make_axes_locatable #make this example reproducible np.random.seed(1) #create chart fig, ax = plt.subplots() im = ax.imshow(np.random.rand(15,15)) ax.set_xlabel('x-axis label') #add color bar fig.colorbar(im) plt.show()
Example 2: Position Colorbar Below Chart
The following code shows how to place a colorbar below a Matplotlib chart:
import numpy as np import matplotlib.pyplot as plt from mpl_toolkits.axes_grid1 import make_axes_locatable #make this example reproducible np.random.seed(1) #create chart fig, ax = plt.subplots() im = ax.imshow(np.random.rand(15,15)) ax.set_xlabel('x-axis label') #add color bar below chart divider = make_axes_locatable(ax) cax = divider.new_vertical(size='5%', pad=0.6, pack_start=True) fig.add_axes(cax) fig.colorbar(im, cax=cax, orientation='horizontal') plt.show()
Note that the pad argument creates padding between the x-axis of the chart and the colorbar. The higher the value for pad, the further away the colorbar will be from the x-axis.
Example 3: Position Colorbar Above Chart
The following code shows how to place a colorbar above a Matplotlib chart:
import numpy as np import matplotlib.pyplot as plt from mpl_toolkits.axes_grid1 import make_axes_locatable #make this example reproducible np.random.seed(1) #create chart fig, ax = plt.subplots() im = ax.imshow(np.random.rand(15,15)) ax.set_xlabel('x-axis label') #add color bar below chart divider = make_axes_locatable(ax) cax = divider.new_vertical(size='5%', pad=0.4) fig.add_axes(cax) fig.colorbar(im, cax=cax, orientation='horizontal') plt.show()
You can find more Matplotlib tutorials here.
