Need help with Python collections code challenge

Question

Hi, I'm trying to solve the combo code challenge. Please see the code that I've written and help in finding the mistake.

Thanks for your help.

zippy.py

# combo([1, 2, 3], 'abc')
# Output:
# [(1, 'a'), (2, 'b'), (3, 'c')]
# If you use .append(), you'll want to pass it a tuple of new values.
my_list = []
def combo(list, str):
  x = 0
  for value in enumerate(str):
    b = value[x]
    a = list[x]
    c = a, b
    my_list.append(c)
    x = x + 1
    continue
  print(my_list)

Answer 1 · 2015-10-24T16:02:49Z

October 24, 2015 4:02pm

The main issue is needing a return statement, and enumerate returns two values. Need to unpack these in to an index and a value. With an index idx, using x as a counter is no longer needed.

Additional feedback:

The continue statement is not needed. Since it is the last statement in the for block of code, a continue is the implied default action.
Indenting to 4 spaces is the PEP-0008 recommendation.
It is a good practice to not use key words or built-in object names as variable names. str and list are built-in types. Common substitutions are "string" and "lst".
The body of the for loop can be reduced to my_list.append((idx, lst[idx]))

# combo([1, 2, 3], 'abc')
# Output:
# [(1, 'a'), (2, 'b'), (3, 'c')]
# If you use .append(), you'll want to pass it a tuple of new values.
my_list = []
def combo(lst, string):
    # x = 0
    for idx, value in enumerate(string):
        b = idx
        a = lst[idx]
        c = a, b
        my_list.append(c)
        # x = x + 1
        # continue #<-- not needed
    #print(my_list) #<-- use return instead of print
    return my_list #<-- added return

Answer 2 · 2015-10-24T13:19:13Z

October 24, 2015 1:19pm

I modified your code so it will pass. You forgot the return statement, also there's no need to use the x variable as enumerate creates an idx variable instead.

my_list = []
def combo(list, str):
  #x = 0
  for idx, value in enumerate(str):
    b = value
    a = list[idx]
    c = a, b
    my_list.append(c)
    #x = x + 1
    continue
  #print(my_list)

  return my_list

Welcome to the Treehouse Community

Looking to learn something new?

Prateek Batra

Prateek Batra

Need help with Python collections code challenge

2 Answers

Chris Freeman

Chris Freeman

Martin Cornejo Saavedra

Martin Cornejo Saavedra