Referencing Items in a List of Tuples

[Paddy]

On Feb 25, 2:01 am, rshep... at nospam.appl-ecosys.com wrote:
>   While working with lists of tuples is probably very common, none of my
> five Python books or a Google search tell me how to refer to specific items
> in each tuple. I find references to sorting a list of tuples, but not
> extracting tuples based on their content.
>
>   In my case, I have a list of 9 tuples. Each tuple has 30 items. The first
> two items are 3-character strings, the remaining 28 itmes are floats.
>
>   I want to create a new list from each tuple. But, I want the selection of
> tuples, and their assignment to the new list, to be based on the values of
> the first two items in each tuple.
>
>   If I try, for example, writing:
>
> for item in mainlist:
>     if mainlist[item][0] == 'eco' and mainlist[item][1] == 'con':
>       ec.Append(mainlist[item][2:])
>
> python doesn't like a non-numeric index.
>
>   I would really appreciate a pointer so I can learn how to manipulate lists
> of tuples by referencing specific items in each tuple (string or float).
>
> Rich

You might also use list comprehensions to accumulate the values you
need:

ec = [ item[2:]  for item in mainlist  if item[:2] == ['eco','con'] ]

- Paddy.