Python Combine Repeating Elements

Question

I have a list of stings that have some repeating elements that I want to combine into a shorter list.

The original list contents look something like this:

lst = [['0.1', '0', 'RC', '100'],
        ['0.2', '10', 'RC', '100'],
        ['0.3', '5', 'HC', '20'],
        ['0.4', '5', 'HC', '20'],
        ['0.5', '5', 'HC', '20'],
        ['0.6', '5', 'HC', '20'],
        ['0.7', '5', 'HC', '20'],
        ['0.8', '5', 'HC', '20'],
        ['0.9', '10', 'RC', '100'],
        ['1.0', '0', 'RC', '100']]

After running it through the function it would become:

lst = [['0.1', '0', 'RC', '100'],
        ['0.2', '10', 'RC', '100'],
        ['0.3', '5', 'HC', '20'],
        ['0.9', '10', 'RC', '100'],
        ['1.0', '0', 'RC', '100']]

The list will always have this general structure, so essentially I want to combine the list based on whether or not the last 3 columns are exactly the same.

I want it to be a callable function so it would look some thing like:

def combine_list(lst):
    if sublist[1:3] == next_sublist[1:3]:
        let.remove(next_sublist)

My initial research on this showed many methods to remove a sublist based on its index, but that is not necessarily known before hand. I also found the re module, however I have never used it and unsure on how to implement it. Thank you in advanced

Answer 1

If you want to remove sub lists that are the same for the last three elements and consecutive, you would need itertools.groupby keyed on the last three elements:

from itertools import groupby
[next(g) for _, g in groupby(lst, key=lambda x: x[1:])]

#[['0.1', '0', 'RC', '100'],
# ['0.2', '10', 'RC', '100'],
# ['0.3', '5', 'HC', '20'],
# ['0.9', '10', 'RC', '100'],
# ['1.0', '0', 'RC', '100']]