Python : How to avoid numpy RuntimeWarning in function definition?

Question

You can use numpy.errstate which is a built-in context manager. This will let you set the err handing to be within the context of the with statement.

import numpy
# warning is not logged here. Perfect for clean unit test output
with numpy.errstate(divide='ignore'):
    numpy.float64(1.0) / 0.0

I had to do this recently when writing unit tests for some legacy python code.

Use numpy.seterr to control what numpy does in this circumstance: http://docs.scipy.org/doc/numpy/reference/generated/numpy.seterr.html

Use the warnings module to control how warnings are or are not presented: http://docs.python.org/library/warnings.html

To go around this, you could increase the precision by modifying the type of the array elements on which you call your function.

For example, if multiplying array a with large numbers as elements by a large floating point number raises an exception

RuntimeWarning: overflow encountered in multiply

then upon specifying the following

a = np.array(a, dtype=np.float128)

no warning occurs.