CL WU wrote:

Hi, group, I am new to numpy. I have 2 questions for array sort.

1. How to sort an array by its one column or one row? I know python build-in sort() can do it for list by passing own cmp function. but array function sort() will sort each column or row seperately,as I know. I don't want to convert array to list to sort and then convert back to array.

I think you want argsort plus take. For example, the following sorts on the second column of a: a = array([[4,5,6], [1,2,3], [7,8,9]]) arg = argsort(a[:,1]) take(a, arg, 0)

2. How to get the rank of a rank-0 array? The first "rank" means the order of each element after sorting, instead of the "dimension" meaning in numpy. Just like "rank()" function in splus.

If I understand you correctly, you want argsort as mentioned above. Regards, -tim

Thank you

Chunlei

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