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Python Python Collections (Retired) Tuples Combo

Posted by Andrew Ge
Andrew Ge
2,158 Points

Strange Error Message

The goal of the assignment (if it is not explained somewhere on this page) is to make a method that takes two iterables and returns a single list, with each item in the list a tuple of two elements: the nth element from the first iterable and the corresponding element from the other iterable.

So the final product looks like: [(1st of iterable 1, 1st of iterable 2), (2nd of iterable 1, 2nd of iterable 2), ... ]

The error is telling me that instead of getting the tuples in the order of (10, 'T'), it is receiving (10, 'T').

Andrew Ge
Andrew Ge
2,158 Points 
def combo(l1, l2):

      tobereturned = []

      for n in l1:

        for e in l2:

          tup = (n, e)

          tobereturned.append(tup)

      return tobereturned

(strange... I thought I had checked the box that says "include code"; isn't that the default setting? I could have sworn I did not touch it)

[MOD: fixed formatting -cf]

2 Answers

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,404 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,404 Points

Your code is creating n**2 tuples instead of n tuples. The first element of l1 is paired with every element of l2. You want to pull one item from each list and pair them:

def combo(l1, l2):
    tobereturned = []
    for indx, n in enumerate(l1):
        tup = (n, l2[indx])
        tobereturned.append(tup)
    return tobereturned

# you can also use `zip`
def combo(l1, l2):
    return list(zip(l1, l2))
Vladan Grubesic
Vladan Grubesic
3,855 Points
Vladan Grubesic
Vladan Grubesic
3,855 Points

I tried few solutions to this problem and I get the same error. "Expecting (10, 'T'), got (10, 'T')."

I googled for the solution and found this code that works:

def combo(iter1, iter2):
  combo_list = []
  for index, value in enumerate(iter1):
    tuple = value, iter2[index]
    combo_list.append(tuple)
  return combo_list

Original solution was posted by: Pracheeti