Allow overflow for numpy types

Question

I'm trying to get the "normal" overflow/underflow behavior of C-type languages in Python. To my surprise, a RuntimeWarning is raised when I'm trying to get this behavior. Example:

np.uint8(255) + np.uint8(1)
>>> RuntimeWarning: overflow encountered in ubyte_scalars

Is there any way to simulate the desired behavior, i.e., that 255+1 gives 0?

I tried the docs but cannot find this behavior documented.

Answer 1

I believe numpy does give you the correct behavior.

In [1]: np.uint8(255) + np.uint8(1)
/usr/bin/ipython:1: RuntimeWarning: overflow encountered in ubyte_scalars
  #!/usr/bin/python2
Out[1]: 0

You can suppress the warning by running:

In [1]: np.seterr(over='ignore')
Out[1]: {'divide': 'warn', 'invalid': 'warn', 'over': 'warn', 'under': 'ignore'}

In [2]: np.uint8(255) + np.uint8(1)
Out[2]: 0