NumPy: calculate averages with NaNs removed

Question

How can I calculate matrix mean values along a matrix, but to remove nan values from calculation? (For R people, think na.rm = TRUE).

Here

Answer 1

From numpy 1.8 (released 2013-10-30) onwards, nanmean does precisely what you need:

>>> import numpy as np
>>> np.nanmean(np.array([1.5, 3.5, np.nan]))
2.5