Unsure of how to create a tuple of pairs

Question

I am trying to loop through 2 iterables, and go through the indices of each iterable, and pair up the values for those indices. Those pairs created will then be appended to an empty tuple, and that tuple will be appended to an empty list. However, here I get "list object doesn't have an enumerate attribute". What am I missing here? Thanks

zippy.py

# combo(['swallow', 'snake', 'parrot'], 'abc')
# Output:
# [('swallow', 'a'), ('snake', 'b'), ('parrot', 'c')]
# If you use list.append(), you'll want to pass it a tuple of new values.
# Using enumerate() here can save you a variable or two.

def combo(iter1,iter2):
  output=list()
  for index,value in iter1.enumerate(),iter2.enumerate():
    pairs=tuple()
    pairs.append(iter1(value),iter2(value))
  output.append(pairs)
  return output

Answer 1 · 2015-02-08T13:54:58Z

February 8, 2015 1:54pm

There're some issues with your solutions.

for index,value in iter1.enumerate(),iter2.enumerate():, I can see that you're trying to iterate through TWO iterables in parallel, but it's illegal to write it like that and it is incorrect way of using enumerate build-in function, you can only write it for index,value in enumerate(iter1):, this will loop through iter1 and return each of its item along with index.
pairs.append(iter1(value),iter2(value)), you can not append item to a tuple, as tuple is immutable.

Actually this problem tells you that

Assume the iterables will be the same length.

This assumption should make writing the function quite a bit easier, because you now only need to have one loop to loop through both iterables using index value 1, 2, ,3 ....

def combo(iter1,iter2):
  output=[]
  for index in range(len(iter1)):    # 1, 2, 3 ... len(iter1)-1
    # group (iter1[index],iter2[index]) in a tuple and append it to output list
    output.append( (iter1[index],iter2[index]) )
  return output

OR, make use of enumerate().

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

Answer 2 · 2015-02-08T14:35:35Z

February 8, 2015 2:35pm

Thank you for this. For some reason on stack exchange it said you can append items to a tuple, but yes I get the immutability aspect point.

I think your second solution where you effectively append a pair each time is helpful!

Thanks

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Dhruv Ghulati

Dhruv Ghulati

Unsure of how to create a tuple of pairs

2 Answers

William Li

William Li

Dhruv Ghulati

Dhruv Ghulati

William Li

William Li