Say I have a list of tuples like this, where the int is the "id" for this purpose:
records_by_id = [(10, 'bubble1'), (5, 'bubble2'), (4, 'bubble3'), (0, 'bubble4'), (3, 'bubble5'),]
... and I sort this by the first element of the tuple:
records_by_id.sort(key = lambda x: x[0])
... this gives:
[(0, 'bubble4'), (3, 'bubble5'), (4, 'bubble3'), (5, 'bubble2'), (10, 'bubble1'),]
Now, given the number 4, how do I locate the list index of "(4, 'bubble3')"? Obviously these tuples are now sorted by their first element, so a brute force iteration through the list is not ideal. I'm thinking there must be a way of using bisect ... or something similar. Any ideas?
Reuse the sort key for bisecting:
from bisect import bisect_left
records_by_id = [(10, 'bubble1'), (5, 'bubble2'), (4, 'bubble3'), (0, 'bubble4'), (3, 'bubble5'),]
key = lambda x: x[0]
records_by_id.sort(key=key)
index = bisect_left(records_by_id, 4, key=key)
print(index)
If it's possible that the given number doesn't occur, add a check at the end checking whether it actually occurs at the resulting index.