I have a list of boolean masks obtained by applying different search criteria to a dataframe. Here is an example list containing 4 masks:

mask_list = [mask1, mask2, mask3, mask4]

I would like to find the logical or of all of the masks in the list. In other words,

or_mask = mask_list[0] | mask_list[1] | mask_list[2] | mask_list[3]

Is there a compact way to accomplish this for a list containing an arbitrary number of masks? I understand that I can write a for loop as below, but is there a shorter, more pythonic way to do this?

for i in range(len(mask_list)):if i == 0:temp_mask_or = mask_list[i]else:temp_mask_or = temp_mask_or | mask_list[i]

You can use reduce:

or_(x,y) means x|y so this will work:

from operator import or_
or_mask = reduce(or_,mask_list)

Edit: As suggested by JoeCondron, instead of operator.or_ you could use numpy.logical_or which gives the same result but is faster.