# enumerate()¶

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



## Example¶

In [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:

In [3]:
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.