In this lecture we will learn about an extremely useful built-in function: enumerate(). Enumerate allows you to keep a count as you iterate through an object. It does this by returning a tuple in the form (count,element). The function itself is equivalent to:
def enumerate(sequence, start=0):
n = start
for elem in sequence:
yield n, elem
n += 1
lst = ['a','b','c']
for number,item in enumerate(lst):
print number
print item
0 a 1 b 2 c
enumerate() becomes particularly useful when you have a case where you need to have some sort of tracker. For example:
for count,item in enumerate(lst):
if count >= 2:
break
else:
print item
a b
Great! You should now have a good understanding of enumerate and its potential use cases.