List index

Question

based on code below, how to retrieve index of list from n instead of a.
is it possible?
objective, want to do something with list using for loop, and if possible dont want to use variable a in loop.

a = ['a', 'b', 'c', 'd']
for n in a:
if n == 'c':
x = a.index('c')
print(x)

other alternative is set i= 0 before for loop and increase val i by 1 each loop. but prefer a solution that run once only, if n='c', then do something to get index.

Answer 1

Use enumerate. With ~4000 upvotes between the question and answer it's been important to people.

http://stackoverflow.com/questions/522563/accessing-the-index-in-JUMP_LINK__&&__python__&&__JUMP_LINK-for-loops

>>> a=list('Jello')
>>> for idx, val in enumerate(a):
... print(idx, val)
...
0 J
1 e
2 l
3 l
4 o

Answer 2

To make it easier, you could do x = n , or even just print(n) . To make it even shorter, you could cut out that for loop and have it be something like:

if 'c' in a:
cout a.index(c)

Answer 3

@Keto - If I want the second 'l'?

>>> a=list('Jello')
>>> if 'l' in a:
... print( a.index('l'))
...
2 # first l
>>>

Also I don't have 'cout' in Python. Are you using it like this, at question "Can I use C++'s syntax for ostreams: cout ..."

http://norvig.com/python-iaq.html

Answer 4

thanks kirk, now I can use each item in list and have it's index. totally what I need.