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

Solution 1

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.

Solution 2

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

Solution 3

Easy:

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

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

Comments

[ᴀʀᴍᴀɴ]

no need for space between them , also adds a space

[Leejay Schmidt]

@Arman Thanks! Corrected it.

[david]

why did you put the -V in i,v

[Iron Fist]

@dragyitutorial what -V ?...i is the index, v is the item at that index...

[Iron Fist]

@dragyitutorial, I've replaced v with item, does it make sense now?

[david]

ok , learned something , but can the -V be another random letter

[david]

and why do i need to put the item at the index (Sorry for stupid question)

[Iron Fist]

@dragyitutorial .. I suggest you take a read the doc from here

[david]

@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

[Leejay Schmidt]

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.

[david]

@LeejaySchmidt Thanks , really appreciated.

[Leejay Schmidt]

No problem. Have fun learning!

[Tom Zych]

Won't work correctly if there are repeated items. And wow, it's kind of inefficient to do a lookup in every iteration.

[Leejay Schmidt]

@TomZych Good points, and they're well taken. I've updated the answer to reflect this.

[Thierry Lathuille]

The first two pieces of code are really bad advice and should be deleted. Using enumerate is the way to go.

[Leejay Schmidt]

@ThierryLathuille I agree. I have removed the methods that involved a traversal of the list first, and now only recommend enumerating the list.