CODEWITHSUNDEEP
pythonlistgrouping
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Reputation: 483

Group nested lists of tuples by two repeating elements

I have a nested list of tuples:

[[(1236.39, -693.34), (1236.8, -697.38), (1236.39, -697.38)],
[(1236.8, -693.34), (1236.39, -693.34), (1236.8, -697.38)],
[(1240.64, -693.15), (1236.6, -693.56), (1236.6, -693.15)],
[(1240.64, -693.56), (1240.64, -693.15), (1236.6, -693.56)],
[(1237.17, -697.82), (1237.19, -697.34), (1237.0, -697.69)],
[(1237.45, -697.53), ([1237.17, -697.82), (1237.19, -697.34)]]

How to group them by two repeating tuples in the lower list:

[[[(1236.39, -693.34), (1236.8, -697.38), (1236.39, -697.38)],
[(1236.8, -693.34), (1236.39, -693.34), (1236.8, -697.38)]],
[[(1240.64, -693.15), (1236.6, -693.56), (1236.6, -693.15)],
[(1240.64, -693.56), (1240.64, -693.15), (1236.6, -693.56)]],
[(1237.17, -697.82), (1237.19, -697.34), (1237.0, -697.69)],
[(1237.45, -697.53), ([1237.17, -697.82), (1237.19, -697.34)]]

i.e. It's like grouping triangles having the common edge. I tried solution from this question, but it returns me wrong result:

    [[(1236.8, -693.34), (1236.39, -693.34), (1236.8, -697.38)]]
    [[(1240.64, -693.15), (1236.6, -693.56), (1236.6, -693.15)], [(1240.64, -693.56), (1240.64, -693.15), (1236.6, -693.56)]]
    [[(1237.17, -697.82), (1237.19, -697.34), (1237.0, -697.69)], [(1237.45, -697.53), (1237.17, -697.82), (1237.19, -697.34)]]
    [[(1236.39, -693.34), (1236.8, -697.38), (1236.39, -697.38)]]

It correctly groups lists in the middle, but lists on the edge are not grouped.

Upvotes: 0

Views: 101

Answers (1)

Saleem Ali
Saleem Ali

Reputation: 1383

Use itertools.groupby to group the items and a function to check the repeating elements which can be used in groupby as key with functools.cmp_to_key same as mentioned in answers of question you shared.

from itertools import groupby as gby
import functools
def check_common(a, b):
    return 0 if any(key in a for key in b) else -1

Result:

>>> key_common = functools.cmp_to_key(check_common)
>>> groups = [list(group) for key, group in gby(input_list, key=key_common)]
>>> groups
>>> [[[(1236.39, -693.34), (1236.8, -697.38), (1236.39, -697.38)], 
      [(1236.8, -693.34), (1236.39, -693.34), (1236.8, -697.38)]], 
     [[(1240.64, -693.15), (1236.6, -693.56), (1236.6, -693.15)], 
      [(1240.64, -693.56), (1240.64, -693.15), (1236.6, -693.56)]], 
     [[(1237.17, -697.82), (1237.19, -697.34), (1237.0, -697.69)], 
      [(1237.45, -697.53), (1237.17, -697.82), (1237.19, -697.34)]]
    ]

Upvotes: 1

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