Numpy how to iterate over columns of array?

python loops numpy
User picture User · Apr 13, 2012 · Viewed 120.9k times · Source

Suppose I have and m x n array. I want to pass each column of this array to a function to perform some operation on the entire column. How do I iterate over the columns of the array?

For example, I have a 4 x 3 array like

1  99 2
2  14 5
3  12 7
4  43 1

for column in array:
  some_function(column)

where column would be "1,2,3,4" in the first iteration, "99,14,12,43" in the second, and "2,5,7,1" in the third.

Answer

tillsten picture tillsten · Apr 13, 2012

Just iterate over the transposed of your array:

for column in array.T:
   some_function(column)

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