[Solved] Sort a list of two lists by second column in python

baion baion · 2010-02-14 12:29:07

Hello all,
I have a a list of two lists, or 2 dimensional array for the C folks, and I would like to sort it based on the values of the second column. For example:

>>> print list 
[["andrew", 10], ["alex", 18], ["john", 12]]
# the sorted list should look like this
>>> print sortedlist
[["alex", 18], ["john", 12], ["andrew", 10]]

Is there a function or method for doing this or should I wirte one myself? I have looked on the internet but have not found exactly what I want.

Thanks in advance,
baion

Last edited by baion baion (2010-04-09 10:04:22)

Xyne · 2010-02-14 12:58:40

It should be easy to write it yourself. You might want to start here.

Allan · 2010-02-14 13:10:47

import operator
sorted(list, key=operator.itemgetter(1))

Ramses de Norre · 2010-02-14 13:22:22

list.sort(lambda x, y: cmp(x[1], y[1]))

baion baion · 2010-02-14 13:56:11

Xyne: That link is really helpful, I have figured it out.
Allan: This is almost what I wanted. What you propose does sort by the second column, but in ascending order, what I want is in descending order so I use

import operator
sorted(list, key=operator.itemgetter(1), reverse=True)

Ramses de Norre:
I get an error using your code saying

TypeError: must use keyword argument for key function

Perhaps it has to do with the fact that I am using Python 3?

Anyway, thank you people; problem solved.

Last edited by baion baion (2010-02-14 13:57:50)

Ramses de Norre · 2010-02-14 14:13:24

baion baion wrote:

Ramses de Norre:
I get an error using your code saying
TypeError: must use keyword argument for key function
Perhaps it has to do with the fact that I am using Python 3?

Indeed, it seems that the syntax I used has been removed in python3...

Arch Linux

#1 2010-02-14 12:29:07

[Solved] Sort a list of two lists by second column in python

#2 2010-02-14 12:58:40

Re: [Solved] Sort a list of two lists by second column in python

#3 2010-02-14 13:10:47

Re: [Solved] Sort a list of two lists by second column in python

#4 2010-02-14 13:22:22

Re: [Solved] Sort a list of two lists by second column in python

#5 2010-02-14 13:56:11

Re: [Solved] Sort a list of two lists by second column in python

#6 2010-02-14 14:13:24

Re: [Solved] Sort a list of two lists by second column in python

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