Python – Grouped Consecutive Range Indices of Elements

When it is required to get the grouped consecutive range of indices of elements in a list, a defaultdict is created. A simple iteration, along with ‘groupby’ method, ‘len’ method, ‘list’ method and the ‘append’ methods are used.

Example

Below is a demonstration of the same −

from itertools import groupby from collections import defaultdict my_list = [63, 12, 84, 91, 52, 39, 25, 27, 20, 11, 0,9] print("The list is : " ) print(my_list) my_index = 0 my_result = defaultdict(list) for key, sub in groupby(my_list): element = len(list(sub)) my_result[key].append((my_index, my_index + element - 1)) my_index += element print("The resultant dictionary is : ") print(my_result)

Output

The list is : [63, 12, 84, 91, 52, 39, 25, 27, 20, 11, 0, 9] The resultant dictionary is : defaultdict(, {63: [(0, 0)], 12: [(1, 1)], 84: [(2, 2)], 91: [(3, 3)], 52: [(4, 4)], 39: [(5, 5)], 25: [(6, 6)], 27: [(7, 7)], 20: [(8, 8)], 11: [(9, 9)], 0: [(10, 10)], 9: [(11, 11)]})

Explanation

• The required packages are imported into the environment.

• A list of integers is defined and is displayed on the console.

• A value is initialized to 0.

• A default dictionary is created.

• The list is iterated over by applying the ‘groupby’ method on it.

• The initialized value is appended to the empty dictionary.

• This is displayed as the output on the console.