Two Dimensional Python Array: Sort second by First

Question

I have a Multidimensional array in Python.

How do I go about sorting the second array, by the first - all the while keeping it in the same order?

can you provide an example? what do you mean sorting the second by the first and keeping the same order? — Stephen
– Stephen, Commented May 6, 2010 at 14:01
I'm unclear exactly how you want your array(s) sorted. Can you edit your question to provide a simple before/after example of what your array looks like before and after being sorted? — Eli Courtwright
– Eli Courtwright, Commented May 6, 2010 at 14:02

Justin Peel · Accepted Answer · 2010-05-06 14:41:29Z

2

I'm not sure from your answer if this is what you want, but take a look and see. If I have a multidimensional array x:

>>> x = [[100,50,39,69,22,23,19,80,94,72],range(10)]
>>> print x
[[100, 50, 39, 69, 22, 23, 19, 80, 94, 72], [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]]

and I want to sort the second subarray by the first subarray, I could do the following:

>>> x[1].sort(key = x[0].__getitem__)
>>> print x
[[100, 50, 39, 69, 22, 23, 19, 80, 94, 72], [6, 4, 5, 2, 1, 3, 9, 7, 8, 0]]

Is that what you're looking for?

answered May 6, 2010 at 14:41

Justin Peel

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2 Comments

Xavier Ho Over a year ago

Can you explain what kind of order this is sorting against?

Justin Peel Over a year ago

It's like the 0 in the second array is has a value of 100 attached to it that is its 'sort value or key' and 1 in the second array has 50 as its sort value and so forth (2 has sort value 39, 3 has sort value 69). I'm sorting the second array by the values of the first array. That was my guess as to what the OP was asking.

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