How to plot a bar chart with a colorbar using matplotlib in python ?

Examples of how to plot a bar chart with a colorbar with matplotlib:

Plot a bar chart with a colorbar (Example 1)

An example of how to associate a color to each bar and plot a color bar

import matplotlib.pyplot as plt
from matplotlib.cm import ScalarMappable

data_x = [0,1,2,3]
data_hight = [60,60,80,100]
data_color = [200.,600.,0.,750.]

data_color_normalized = [x / max(data_color) for x in data_color]

fig, ax = plt.subplots(figsize=(15, 4))

my_cmap = plt.cm.get_cmap('GnBu')
colors = my_cmap(data_color_normalized)

rects = ax.bar(data_x, data_hight, color=colors)

sm = ScalarMappable(cmap=my_cmap, norm=plt.Normalize(0,max(data_color)))

sm.set_array([])

cbar = plt.colorbar(sm)
cbar.set_label('Color', rotation=270,labelpad=25)

plt.xticks(data_x)    
plt.ylabel("Y")

plt.title('How to plot a bar chart with a colorbar with matplotlib ?')

plt.savefig("bar_chart_with_colorbar_01.png", bbox_inches='tight')

plt.show()

Plot a bar chart with a colorbar: color normalized (Example 2)

To normalize the color between 0 and 1, just replace

sm = ScalarMappable(cmap=my_cmap, norm=plt.Normalize(0,max(data_color)))

to

sm = ScalarMappable(cmap=my_cmap, norm=plt.Normalize(0,max(data_color_normalized)))

Plot a bar chart with a colorbar: color associated to bar height (Example 3)

Another example: using a colorbar to show bar height

import matplotlib.pyplot as plt
from matplotlib.cm import ScalarMappable

data_x = [0,1,2,3]
data_hight = [60,60,80,100]

data_hight_normalized = [x / max(data_hight) for x in data_hight]

fig, ax = plt.subplots(figsize=(15, 4))

my_cmap = plt.cm.get_cmap('GnBu')
colors = my_cmap(data_hight_normalized)

rects = ax.bar(data_x, data_hight, color=colors)

sm = ScalarMappable(cmap=my_cmap, norm=plt.Normalize(0,max(data_hight)))

sm.set_array([])

cbar = plt.colorbar(sm)
cbar.set_label('Color', rotation=270,labelpad=25)

plt.xticks(data_x)    
plt.ylabel("Y")

plt.title('How to plot a bar chart with a colorbar with matplotlib ?')

plt.savefig("bar_chart_with_colorbar_03.png", bbox_inches='tight')

plt.show()

References

• Python: Barplot with colorbar
• pyplot/matplotlib Bar chart with fill color depending on value
• matplotlib bar plot add legend from categories dataframe column