[Numpy-discussion] Finding indices for all rows which contain nan (or anything else)

Webb Sprague webb.sprague at gmail.com
Thu Jul 13 14:42:30 CDT 2006

Does anyone have some vectorized code that pulls out all the row
indices for any row which has an nan (or a number less than 1 or
whatever).  I want to subsequently be able to perform an operation
with all the good rows.  See the imaginary code below.

a = numpy.array([[1,2],[nan,1], [2,3]])
is_row_nan(a) == array([1])
ii = numpy.negative(is_row_nan(a))

a[ii,:] # these are the ones I want.  Hopefully this is array([[1,2],[2,3]])

I can imagine doing this with a loop or with (maybe) some fancy set
union stuff, but I am at a loss for vectorized versions.


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