如何在严格增加的python列表中有效查找元素的序数？

Question

I can only think of iterating through the list, but that's highly inefficient as the list can grow as big as 1000000.

EDIT : I also know about binary search. I would like to know if there is any builtin python function which can do this efficiently.

Answer 1

Take a look at the bisect module. The docs suggest the following for locating an element in a sorted list:

def index(a, x):
    'Locate the leftmost value exactly equal to x'
    i = bisect_left(a, x)
    if i != len(a) and a[i] == x:
        return i
    raise ValueError