How to change color in pie chart using Matplotlib - python-3.x

Question

I am trying to make v1 as blue, v2 as orange, v3 green and v4 as light grey
I tried going through documentation but cannot understand how to define color in piechart. Thank you for help.
I am using few line of codes of generate a piechart
where vol1 = v1,v2,v3,v4
plt.pie(vol1,labels = vollabels, autopct="%0.2f%%")
plt.legend(title="Normalized Volumes",loc="upper left", fontsize=14)
plt.axis
plt.show()

Answer 1

If you want to have control over which colors your pie chart contains, while at the same time not fall out of matplotlib's convenient handling of colour maps, you might want to have a look at documentation example Nested pie charts. Extracted highlights:
import matplotlib.pyplot as plt
import numpy as np
Retrieve a named colour map and "hand-pick", using a numbered range, suitable colors. The index picking in inner_colors matches hues for a larger numbers of data points in the inner circle:
cmap = plt.get_cmap("tab20c")
outer_colors = cmap(np.arange(3)*4)
inner_colors = cmap(np.array([1, 2, 5, 6, 9, 10]))
The actual plotting, including some customisation, is then straightforward:
fig, ax = plt.subplots()
size = 0.3
vals = np.array([[60., 32.], [37., 40.], [29., 10.]])
ax.pie(vals.sum(axis=1), radius=1, colors=outer_colors,
wedgeprops=dict(width=size, edgecolor='w'))
ax.pie(vals.flatten(), radius=1-size, colors=inner_colors,
wedgeprops=dict(width=size, edgecolor='w'))
Bonus content in the linked location: how to achieve the same result using a bar plot, but using polar coordinates. That way, one has more flexibility over the exact design, if one's goals diverge from the defaults assumed in pie.