bisect(haystack, needle) does a binary search for needle in haystack — which must be a sorted sequence — to locate the position where needle can be inserted while maintaining haystack in ascending order. In other words, all items appearing up to that position are less or equal to needle.

Graphic.py

import bisect
import sys
HAYSTACK = [1, 4, 5, 6, 8, 12, 15, 20, 21, 23, 23, 26, 29, 30]
NEEDLES = [0, 1, 2, 5, 8, 10, 22, 23, 29, 30, 31]
ROW_FMT = '{0:2d} @ {1:2d} {2}{0:<2d}'
def demo(bisect_fn):
 for needle in reversed(NEEDLES):
 position = bisect_fn(HAYSTACK, needle) 
 offset = position * ' |' 
 print(ROW_FMT.format(needle, position, offset)) 
if __name__ == '__main__':
 if sys.argv[-1] == 'left':
bisect_fn = bisect.bisect_left
 else:
 bisect_fn = bisect.bisect
 print('DEMO:', bisect_fn.__name__) 
 print('haystack ->', ' '.join('%2d' % n for n in HAYSTACK))
 demo(bisect_fn)