I have 2 lists
in1=[1,1,1,2,2,3,4,4,4,5,5]
in2=['a','b','c','d','e','f','g','h','i','j','k']
I want to group the second list based on the same elements in the first list i.e.
Output has to be
out=[['a','b','c'],['d','e'],['f'],['g','h','i'],['j','k']]
Explanation: the first 3 elements of the first list are the same, so I want the first 3 elements of the 2nd list to be grouped together (and so on)
If anyone can help out, it would be great!
~Thanks
CodePudding user response:
Just zip
the lists, then itertools
to the rescue.
from itertools import groupby
in1 = [1,1,1,2,2,3,4,4,4,5,5]
in2 = ['a','b','c','d','e','f','g','h','i','j','k']
result = [[c for _, c in g] for _, g in groupby(zip(in1, in2), key=lambda x: x[0])]
print(result)
# [['a', 'b', 'c'], ['d', 'e'], ['f'], ['g', 'h', 'i'], ['j', 'k']]
Non-itertools
solution:
in1 = [1,1,1,2,2,3,4,4,4,5,5]
in2 = ['a','b','c','d','e','f','g','h','i','j','k']
result = [[]]
key = in1[0]
for k, v in zip(in1, in2):
if k != key:
result.append([])
key = k
result[-1].append(v)
print(result)
# [['a', 'b', 'c'], ['d', 'e'], ['f'], ['g', 'h', 'i'], ['j', 'k']]