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Python – Grouped Consecutive Range Indices of Elements

  • Last Updated : 02 Sep, 2020

Given List of elements, for list of tuples, where each represents the continuity of occurrence of each element.

Input : test_list = [1, 1, 5, 6, 5, 5]
Output : {1: [(0, 1)], 5: [(2, 2), (4, 5)], 6: [(3, 3)]}
Explanation : 5 present at 2nd idx and also in continuation in 4th and 5th index, and hence recorded range.

Input : test_list = [5, 5, 5, 5, 5, 5]
Output : {5: [(0, 5)]}
Explanation : Only 5 present, hence recorded.

Method : Using groupby() + defaultdict() + len() + loop

In this, we perform consecutive elements grouping using groupby(), defaultdict() is used to initialize the tuple list, The len() is used to get length of repetition.

Python3




# Python3 code to demonstrate working of 
# Grouped Consecutive Range Indices of Elements
# Using groupby() + defaultdict() + len() + loop
from itertools import groupby
from collections import defaultdict
  
# initializing lists
test_list = [1, 1, 5, 6, 5, 5, 6, 6, 6, 1, 5, 5]
  
# printing string
print("The original list : " + str(test_list))
  
idx = 0
res = defaultdict(list)
  
# grouping Consecutives
for key, sub in groupby(test_list):
    ele = len(list(sub))
      
    # append strt index, and till index
    res[key].append((idx, idx + ele - 1))
    idx += ele
  
# printing results 
print("The grouped dictionary : " + str(dict(res)))
Output
The original list : [1, 1, 5, 6, 5, 5, 6, 6, 6, 1, 5, 5]
The grouped dictionary : {1: [(0, 1), (9, 9)], 5: [(2, 2), (4, 5), (10, 11)], 6: [(3, 3), (6, 8)]}

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