ValueError: invalid number of points for pie

ValueError: invalid number of points for pie

$ python -c "import matplotlib.pyplot as plt; plt.pie([])"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ValueError: Wedge sizes 'x' must be non negative values

Why this happens

You passed an empty list or negative values to pie.

Fix

Provide non-empty, non-negative sizes.

Wrong code

import matplotlib.pyplot as plt
plt.pie([])

Fixed code

import matplotlib.pyplot as plt
plt.pie([30, 40, 30])
plt.show()