TypeError: "NoneType" object does not support element assignment

Question

I am trying to do a math calculation according to the values ​​in a specific index of a NumPy array with the following code

X = np.arange(9).reshape(3,3)
temp = X.copy().fill(5.446361E-01)
ind = np.where(X < 4.0)
temp[ind] = 0.5*X[ind]**2 - 1.0
ind = np.where(X >= 4.0 and X < 9.0)
temp[ind] = (5.699327E-1*(X[ind]-1)**4)/(X[ind]**4)
print temp

But I get the following error:

Traceback (most recent call last):
File "test.py", line 7, in <module>
temp[ind] = 0.5*X[ind]**2 - 1.0 
TypeError: 'NoneType' object does not support item assignment

Could you help me solve this? Thanks

Answer 1

fill returns nothing.

>>> import numpy as np
>>> X = np.arange(9).reshape(3,3)
>>> temp = X.copy()
>>> return_value_of_fill = temp.fill(5.446361E-01)
>>> return_value_of_fill is None
True

Replace the following line:

temp = X.copy().fill(5.446361E-01)

from:

temp = X.copy()
temp.fill(5.446361E-01)