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I have a list 

list1 = [[a,   e,   o,   i,   u], 
     [3.0, 2.0, 1.0, 5.0, 4.0], 
     [5.1, 4.7, 2.5, 3.2, 1.1]]

I want to sort this list based on the 2nd list. i.e. the middle one. The result should be as follows

sorted_list1 = [[o,   e,   a,   u,   i],
            [1.0, 2.0, 3.0, 4.0, 5.0],
            [2.5, 4.7, 5.1, 1.1, 3.2]

Please mention the supporting import modules as well if required.

Note: I have equal number of elements in each list.

ranjith konaje
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  • `zip(*sorted(zip(*list1), key=lambda c: c[1]))` should do this (transpose, sort on middle column, transpose again). You may need to add `list()` in Python 3, or wrap in `[list(r) for r in ...]` to output a list of lists again. – Martijn Pieters Apr 24 '17 at 11:56
  • Thanks. This answer works. Is python able to sort only based on columns? – ranjith konaje Apr 24 '17 at 12:02
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    sorting applies to a *single sequence*. You have 3 sequences, so I combined them into one sequence containing tuples of 3 values each, then reverse the process after sorting. – Martijn Pieters Apr 24 '17 at 12:03
  • In Python 3.6 you can also do `[*map(list, zip(*sorted(zip(*list1), key=lambda c: c[1])))]` if you _really_ need a list of lists instead of a list of tuples. – PM 2Ring Apr 24 '17 at 12:10

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