ValueError: bins must be monotonically increasing

ValueError: bins must be monotonically increasing

$ python plot.py
Traceback (most recent call last):
  ...
ValueError: bins must be monotonically increasing or equal

Why this happens

When defining custom bins for a histogram using plt.hist(), the array of bin edges must be sorted in ascending order.

Fix

Sort your bins array before passing it to the histogram function.

Wrong code

import matplotlib.pyplot as plt

data = [1, 2, 3, 4, 5]
bins = [0, 5, 2, 10] # Not sorted
plt.hist(data, bins=bins)

Fixed code

import matplotlib.pyplot as plt

data = [1, 2, 3, 4, 5]
bins = [0, 2, 5, 10] # Sorted
plt.hist(data, bins=bins)