Reference an Element in a List of Tuples

python list reference element tuples
Turner Hughes picture Turner Hughes · Jun 23, 2011 · Viewed 110.9k times · Source

Sorry in advance, but I'm new to Python. I have a list of tuples, and I was wondering how I can reference, say, the first element of each tuple within the list. I would think it's something like 

for i in number_of_tuples :
  first_element = myList[i[0]]

you know, [list_element[tuple_element]]? However, this doesn't appear to be the right approach. Any help would be greatly appreciated.

Thanks,

Turner

Answer

Prodigal Maestro picture Prodigal Maestro · Jun 23, 2011

All of the other answers here are correct but do not explain why what you were trying was wrong. When you do myList[i[0]] you are telling Python that i is a tuple and you want the value or the first element of tuple i as the index for myList.

In the majority of programming languages when you need to access a nested data type (such as arrays, lists, or tuples), you append the brackets to get to the innermost item. The first bracket gives you the location of the tuple in your list. The second bracket gives you the location of the item in the tuple.

This is a quick rudimentary example that I came up with:

info = [ ( 1, 2), (3, 4), (5, 6) ]

info[0][0] == 1
info[0][1] == 2
info[1][0] == 3
info[1][1] == 4
info[2][0] == 5
info[2][1] == 6

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