Nested list and sorting in python

Question

I don't know if it is possible or not. I am trying to find a way of sorting a nested list on the following condition

i want to sort form 1 point to another (NOT the whole list only part of it)
the sorting should be done on the basis of 3rd element of the sublists

an Idea of what i want:

    PAE=[['a',0,8],
         ['b',2,1],
         ['c',4,3],
         ['d',7,2],
         ['e',8,4]]

    #PAE[1:4].sort(key=itemgetter(2))  (something like this)    
    or    
    #sorted(PAE[1:4],key=itemgetter(2))  (something like this)  
`   # ^ i know both are wrong but just for an idea
`
    #output should be like this  
    ['a', 0, 8]
    ['b', 2, 1]
    ['d', 7, 2]
    ['c', 4, 3]
    ['e', 8, 4]

I am new to python, but i tried my level best to find a solution but failed.

Stefan Pochmann · Accepted Answer · 2016-11-24 11:29:14Z

3

Sort the slice and write it back:

>>> PAE[1:4] = sorted(PAE[1:4], key=itemgetter(2))
>>> PAE
[['a', 0, 8], ['b', 2, 1], ['d', 7, 2], ['c', 4, 3], ['e', 8, 4]]

answered Nov 24, 2016 at 11:29

Stefan Pochmann

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Comments

Eric Duminil · Accepted Answer · 2016-11-24 11:07:42Z

3

This should do :

from operator import itemgetter
PAE=[['a',0,8],
    ['b',2,1],
    ['c',4,3],
    ['d',7,2],
    ['e',8,4]]

split_index = 1

print PAE[:split_index]+sorted(PAE[split_index:],key=itemgetter(2))
#=> [['a', 0, 8], ['b', 2, 1], ['d', 7, 2], ['c', 4, 3], ['e', 8, 4]]

answered Nov 24, 2016 at 11:07

Eric Duminil

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Comments

Ari Gold · Accepted Answer · 2016-11-24 11:48:01Z

0

here without spliting, question is whats is the best for readability

PAE=[['a',0,8],
    ['b',2,1],
    ['c',4,3],
    ['d',7,2],
    ['e',8,4]]

print (sorted(PAE, key=lambda PAE: PAE[1] if not PAE[1] else PAE[2]))
>>> [['a', 0, 8], ['b', 2, 1], ['d', 7, 2], ['c', 4, 3], ['e', 8, 4]]

edited Nov 24, 2016 at 11:48

answered Nov 24, 2016 at 11:30

Ari Gold

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6 Comments

Eric Duminil Over a year ago

I don't think it answers the question. Your sort depends on the second element of each list, right?

Ari Gold Over a year ago

NO Eric, the sort key is relative in this case

Eric Duminil Over a year ago

Yes, but the question didn't mention it.

Eric Duminil Over a year ago

Let the OP decide. It matches the expectation for this exact example. But wouldn't work with ['a', 1, 8] as the first list.

Syed Over a year ago

Thank you for for trying Ari :) , but as Eric mentioned its for one particular case. But i wanted, is a generalized solution. Check Stephan and Eric's solutions both worked perfectly.

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