Append values in a 2d python list

Question

I have got a list in python

issuelist=[["k1","v1"],["k2","v2"],["k3","v1"],["k4","v2"],["k5","v2"],["k6","v3"],["k7","v1"]]

I want to append the values of this list into another list in such a way that if value of issuelist[x][1]==issuelist[y][1] I can get something like this

Buildlist=[["k1","k3","k7"],["k2","k4","k5"],["k6"]]

issuelist=[["k1","v1"],["k2","v2"],["k3","v1"],["k4","v2"],["k5","v2"],["k6","v3"],["k7","v1"]]
count=len(issuelist)
buildlist = [[]]* count
for i in range(len(issuelist)):
    for j in range(len(issuelist)):
        if issuelist[i][1]==issuelist[j][1]:
            buildlist[i].append(issuelist[j][0])

This is what I have tried now but I could not get the desirerd result. Any help would be appreciated

This is input => issuelist = [["k1","v1"],["k2","v2"],["k3","v1"],["k4","v2"],["k5","v2"],["k6","v3"],["k7","v1"]]. What kind of output you are expecting ? — gachdavit
– gachdavit, Commented May 22, 2019 at 9:02

Rakesh · Accepted Answer · 2019-05-22 09:03:47Z

4

Use itertools.groupby

Ex:

from itertools import groupby

issuelist = [["k1","v1"],["k2","v2"],["k3","v1"],["k4","v2"],["k5","v2"],["k6","v3"],["k7","v1"]]
result = {k: [i[0] for i in v ]for k, v in groupby(sorted(issuelist, key=lambda x: x[1]), lambda x: x[1])}
print(result)
print(list(result.values()))

Output:

{'v1': ['k1', 'k3', 'k7'], 'v2': ['k2', 'k4', 'k5'], 'v3': ['k6']}
[['k1', 'k3', 'k7'], ['k2', 'k4', 'k5'], ['k6']]

answered May 22, 2019 at 9:03

Rakesh

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Faizan Naseer · Accepted Answer · 2019-05-22 09:12:50Z

0

try this:

from collections import defaultdict
issuelist = [["k1","v1"],["k2","v2"],["k3","v1"],["k4","v2"],["k5","v2"],["k6","v3"],["k7","v1"]]
result = defaultdict(list)
for inner_list in issuelist:
    result[inner_list[1]].append(inner_list[0])

result_array = list(result.values())
rint(presult_array)

answered May 22, 2019 at 9:12

Faizan Naseer

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