python enumerate()

I have seen the enumerate() function many times in other peoples scripts, but I have never known what it does exactly, and why someone would prefer using it.

Enumerate means to "mention a list of items, one by one." So, it would be most useful in loops over a list.

The built in enumerate() function lists the items in a list along side their index number:

order_list = ['fist', 'second', 'third']
for i in enumerate(order_list):
   print i

(0, 'fist')
(1, 'second')
(2, 'third')

This is useful for getting the index values of a list:

for i, order in enumerate(order_list):
    print i, order

0 fist
1 second
2 third

Thus, this function is a better way of looping over a certain list:

for i in range(len(order_list)):
    print i, order_list[i]

0 fist
1 second
2 third

Why is enumerate() better than range(len())? Because it is one function instead of two nested functions!

You may also iterate through each item of a list without a loop by using the next function:

items = enumerat(order_list)

items.next()

items.next()

items.next()

See more here: http://www.juniordevelopercentral.com/python-enumerate-function/