[FIXED] How to concatenate string values in two lists without creating duplicates?

Issue

I have two lists that I am trying to join. They two become one. A partial match between the values is used to merge the values.

list1 = ["15:09.123", "15:09.234", "15:09.522", "15:09.621", "15:10.123", "15:11.123", "15:12.123", "15:12.987"]
list2 = ["15:09", "15:09", "15:10", "15:14"]
final = []
for each in list2:
    for each1 in list1:
        if each in each1:
            eachtemp = each1.split(".")[1]
            final.append(each+"."+eachtemp)
            list1.remove(each1)
print(final)

This produces an output

['15:09.123', '15:09.522', '15:09.234', '15:10.123']

But ideal output I want is

['15:09.123', '15:09.234', '15:10.123', '15:14.000']

It should not contain "15:09.522", "15:09.621" even though they have partially matching elements in the list1. The final list should contain all elements in list2 with 3 more digits acquired from list1 and final list should be the same length as list2.

Solution

I might suggest using an iterator over list1 and consuming elements from it as you iterate over list2 (renaming these ms_list and s_list to make it easier to keep track of which is which):

>>> ms_list = ["15:09.123", "15:09.234", "15:09.522", "15:09.621", "15:10.123", "15:11.123", "15:12.123", "15:12.987"]
>>> s_list = ["15:09", "15:09", "15:10", "15:14"]
>>> final = []
>>> ms_iter = iter(ms_list)
>>> for s in s_list:
...     default = f"{s}.000"
...     ms = next(ms_iter, default)
...     while not ms.startswith(s) and ms < s:
...         ms = next(ms_iter, default)
...     final.append(ms if ms.startswith(s) else default)
...
>>> final
['15:09.123', '15:09.234', '15:10.123', '15:14.000']

Answered By - Samwise