grouping list of list in python for a particular element

Question

I have a list of list

List = [['ServerA','Envname1','abc','xyz'],
        ['ServerA','Envname2','abc','xyz'],
        ['ServerB','Envname3','aaa','bbb'],
        ['ServerC','EnvName4','uuu','vvv'],
        ['ServerB','Envname5','aaa','bbb']]

If the server is same then the values at 2nd and 3rd index of the inner lists will be same.

For example:- In the 1st list ['ServerA','Envname1','abc','xyz'] and 2nd list ['ServerA','Envname2','abc','xyz'] server is same ('ServerA') so the values 'abc' and 'xyz' is same.

Likewise, values for ServerB in the 3rd and 4th is same 'aaa' and 'bbb'

Only the Envname is changing even if the server is same.

What i want in my final list of list is to group all the servers which has the same name and add all the Envnames in them accordingly, rest of the elements will be the same if the server name is same.

Expected List

Final_list = [['ServerA','Envname1,Envname2','abc','xyz'],
              ['ServerB','Envname3,Envname5','aaa','bbb'],
              ['ServerC','EnvName4','uuu','vvv']]

Can anybody advise me on this?

Jamie Cockburn · Accepted Answer · 2014-07-01 10:09:36Z

2

This should work:

l = [['ServerA','Envname1','abc','xyz'],
     ['ServerA','Envname2','abc','xyz'],
     ['ServerB','Envname3','aaa','bbb'],
     ['ServerC','EnvName4','uuu','vvv'],
     ['ServerB','Envname5','aaa','bbb'],
     ]

d = {}
for item in l:
    key = (item[0], item[2], item[3])
    env = d.setdefault(key, [])
    env.append(item[1])

final_list = [[k[0], ",".join(v), k[1], k[2]] for k, v in d.items()]
print final_list

Output:

[['ServerA', 'Envname1,Envname2', 'abc', 'xyz'],
 ['ServerB', 'Envname3,Envname5', 'aaa', 'bbb'],
 ['ServerC', 'EnvName4', 'uuu', 'vvv'],
 ]

edited Jul 1, 2014 at 10:09

answered Jul 1, 2014 at 9:17

Jamie Cockburn

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Comments

sundar nataraj · Accepted Answer · 2014-07-01 09:20:07Z

0

from itertools import groupby,chain
from operator import itemgetter
List_server = [['ServerA','Envname1','abc','xyz'],
        ['ServerA','Envname2','abc','xyz'],
        ['ServerB','Envname3','aaa','bbb'],
        ['ServerC','EnvName4','uuu','vvv'],
        ['ServerB','Envname5','aaa','bbb']]

List_server=sorted(List,key=lambda x:x[0][-1])
print [set(chain(*list(g))) for i,g in groupby(List_server,key=itemgetter(0))]

output: [set(['xyz', 'abc', 'ServerA', 'Envname2', 'Envname1']),
         set(['Envname5', 'aaa', 'bbb', 'ServerB', 'Envname3']), 
         set(['EnvName4', 'uuu', 'vvv', 'ServerC'])]

explantion:

First sort your list according to servers List_server=sorted(List,key=lambda x:x[0][-1])
Perform Groupby by using key=itemgetter(0)

Note: Do not use Python Keywords as variables

edited Jul 1, 2014 at 9:20

answered Jul 1, 2014 at 9:16

sundar nataraj

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1 Comment

Jamie Cockburn Over a year ago

The OP asked that the env names be joined with commas. You are also not preserving the ordering of the sub-lists, which might be important.

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