How do I display the the index of a list element in Python?

Question

I have a homework assignment. I've got the following code

hey = ["lol", "hey","water","pepsi","jam"]

for item in hey:
    print(item)

Do I display the position in the list before the item, like this:

1 lol
2 hey
3 water
4 pepsi
5 jam

Note all the "+1"s in the answers. Python starts with an index of 0, not 1. So the proper positions are 0, 1, 2, 3, 4 — mauve, Jan 12 '16 at 21:45

Leejay Schmidt · Accepted Answer · 2020-05-05T17:33:02.537

13

The best method to solve this problem is to enumerate the list, which will give you a tuple that contains the index and the item. Using enumerate, that would be done as follows.

In Python 3:

for (i, item) in enumerate(hey, start=1):
    print(i, item)

Or in Python 2:

for (i, item) in enumerate(hey, start=1):
    print i, item

If you need to know what Python version you are using, type python --version in your command line.

edited May 05 '20 at 17:33

answered Jan 12 '16 at 21:23

Leejay Schmidt

1,038
14
24

no need for space between them `,` also adds a space – ᴀʀᴍᴀɴ Jan 12 '16 at 21:25
@Arman Thanks! Corrected it. – Leejay Schmidt Jan 12 '16 at 21:25
@LeejaySchmidt im in high school , so can you explain to me what does --hey.index(item)+1,item-- mean , i dont uderstand why did you put --index(item)+1 and why did you put --,item at the end – david Jan 12 '16 at 22:55
Arrays in Python start indexing at `0`, so you have to have `index(item)+1` to start printing the indexes at `1` instead of `0` (otherwise you would get `0 lol` and `1 hey`, etc.). The `,item` concatenates the `string` representation of the item with what is preceding the comma, otherwise it would just print out the index. – Leejay Schmidt Jan 12 '16 at 23:01
@LeejaySchmidt Thanks , really appreciated. – david Jan 12 '16 at 23:07
No problem. Have fun learning! – Leejay Schmidt Jan 12 '16 at 23:08
Won't work correctly if there are repeated items. And wow, it's kind of inefficient to do a lookup in every iteration. – Tom Zych Jan 13 '16 at 00:58
@TomZych Good points, and they're well taken. I've updated the answer to reflect this. – Leejay Schmidt Jan 13 '16 at 01:32
The first two pieces of code are really bad advice and should be deleted. Using `enumerate` is the way to go. – Thierry Lathuille Apr 23 '20 at 19:03
@ThierryLathuille I agree. I have removed the methods that involved a traversal of the list first, and now only recommend enumerating the list. – Leejay Schmidt May 05 '20 at 17:34

Iron Fist · Answer 2 · 2016-01-12T22:17:58.763

7

Use the start parameter of the enumerate buit-in method:

>>> hey = ["lol", "hey","water","pepsi","jam"]
>>> 
>>> for i, item in enumerate(hey, start=1):
    print(i,item)


1 lol
2 hey
3 water
4 pepsi
5 jam

edited Jan 12 '16 at 22:17

answered Jan 12 '16 at 22:06

Iron Fist

9,767
2
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why did you put the -V in i,v – david Jan 12 '16 at 22:13
@dragyitutorial what -V ?...i is the index, v is the item at that index... – Iron Fist Jan 12 '16 at 22:17
@dragyitutorial, I've replaced v with item, does it make sense now? – Iron Fist Jan 12 '16 at 22:18
ok , learned something , but can the -V be another random letter – david Jan 12 '16 at 22:19
and why do i need to put the item at the index (Sorry for stupid question) – david Jan 12 '16 at 22:20
@dragyitutorial .. I suggest you take a read the doc from [here](https://docs.python.org/3/library/functions.html#enumerate) – Iron Fist Jan 12 '16 at 22:48

Baerus · Answer 3 · 2016-01-12T21:35:35.750

3

Easy:

hey = ["lol","hey","water","pepsi","jam"]

for (num,item) in enumerate(hey):
    print(num+1,item)

edited Jan 12 '16 at 21:35

answered Jan 12 '16 at 21:30

Baerus

79
1
8

How do I display the the index of a list element in Python?

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