How to generate color based on the magnitude of the values in python?

Question

I am trying to make a Bar plot in python so that the color of each bar is set based on the magnitude of that value. For example the list below is our numbers:

List = [2,10,18,50, 100, ... 500]

In this situation 2 should have the lightest color and 500 should have the darkest color values. The picture below which is from excel shows what i mean:

I appreciate answers which helps me.
Thank you.

Update:

import matplotlib.pyplot as plt

fig, ax = plt.subplots()

names= ['A', 'B', 'C', 'D']
counts = [30, 40, 55, 100]
bar_colors = ['blue']

ax.bar(names, counts,  color=bar_colors)
ax.set_ylabel('Frequency')
ax.set_title('Names')
plt.show()

Asked By: hamid

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Source

Answer 1

Then you can use a Colormap (extra docs) from matplotlib

In this example the bar_colors list is being creating with a scale between 0 and 100 but you can choose the scale as you want.

import matplotlib.pyplot as plt
import matplotlib.colors
fig, ax = plt.subplots()

names= ['A', 'B', 'C', 'D', 'E']
counts = [10, 30, 40, 55, 100]

cmap = matplotlib.colors.LinearSegmentedColormap.from_list("", ["red","orange", "green"])

bar_colors = [cmap(c/100) for c in counts]

ax.bar(names, counts,  color=bar_colors)
ax.set_ylabel('Frequency')
ax.set_title('Names')
plt.show()

Please, notice you can instantiate the cmap with a list of colors as you desire.

Also, be sure that when invoking cmap() you just can use a float between [0,1].

Answered By: fernandezr

How to generate color based on the magnitude of the values in python?

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