Tag: nested-lists

Splitting a List Based on a Substring

I have the following list:

['1(Reg)', '100', '103', '102', '100', '2(Reg)', '98', '101', '100', '3(Reg)', '96', '99', '98', '4(Reg)', '100', '100', '100', '100', '5(Reg)', '98', '99', '99', '100', '6(Reg)', '99.47', '99.86', '99.67', '100']

I want to split this list into multiple lists so that each sublist will have the substring “(Reg)” appear once:

[['1(Reg)', '100', '103', '102', '100'],
['2(Reg)', '98', '101', '100'],
['3(Reg)', '96', '99', '98'],
['4(Reg)', '100', '100', '100', '100'],
['5(Reg)', '98', '99', '99', '100'],
['6(Reg)', '99.47', '99.86', '99.67', '100']]

I’ve tried joining the list with a delimiter and splitting it by (Reg), but that didn’t work. How can I split the list into a nested list like above?

Solution:

Here is one way, though not necessarily optimal:

from itertools import zip_longest

lst = ['1(Reg)', '100', '103', '102', '100', '2(Reg)', '98', '101', '100',
       '3(Reg)', '96', '99', '98', '4(Reg)', '100', '100', '100', '100',
       '5(Reg)', '98', '99', '99', '100', '6(Reg)', '99.47', '99.86', '99.67', '100']

indices = [i for i, j in enumerate(lst) if '(Reg)' in j]
lst_new = [lst[i:j] for i, j in zip_longest(indices, indices[1:])]

# [['1(Reg)', '100', '103', '102', '100'],
#  ['2(Reg)', '98', '101', '100'],
#  ['3(Reg)', '96', '99', '98'],
#  ['4(Reg)', '100', '100', '100', '100'],
#  ['5(Reg)', '98', '99', '99', '100'],
#  ['6(Reg)', '99.47', '99.86', '99.67', '100']]