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Python Functional Python Functional Workhorses Map

Posted by Abhishek K Das
Abhishek K Das
3,446 Points

Code works locally but not in treehouse editor

backwards = [ 'tac', 'esuoheerT', 'htenneK', [5, 4, 3, 2, 1], ]

def reverse(item): return list(map(lambda x: x[::-1], item))

maps.py 
backwards = [
    'tac',
    'esuoheerT',
    'htenneK',
    [5, 4, 3, 2, 1],
]


def reverse(item):
    return list(map(lambda x: x[::-1], item))

It says 'reverse didn't accept an argument.'

2 Answers

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,460 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,460 Points

Wow! Truly impressive. You've done a great job. It's just more than the challenge actually needed. You only have to reverse the top-level members of the iterable, not reverse the members of the iterable:

# Task 1 of 2
# Create a function named 'reverse' that takes a single iterable item
# and returns a reversed version of that item.
def reverse(iter1):
    return iter1[::-1]
Abhishek K Das
Abhishek K Das
3,446 Points

Yup, thanks :)

Chris Grazioli
Chris Grazioli
31,225 Points

This way seemed more along the lines of the what the prior videos were getting at. Using the built in python stuff and casting it to a list

backwards = [
    'tac',
    'esuoheerT',
    'htenneK',
    [5, 4, 3, 2, 1],
]

def reverse(iter1):
    return list(reversed(iter1))

Refresh my memory on your code now, what does iter1[::-1] mean? I'm guessing its slicing the iterable and listing it in reverse..

Chris Grazioli
Chris Grazioli
31,225 Points

I do run into an issue using the code in the very next challenge however? Why doesn't this work for me?

backwards = [
    'tac',
    'esuoheerT',
    'htenneK',
    [5, 4, 3, 2, 1],
]

def reverse(iter1):
    return list(reversed(iter1))

forwards= list(map(reverse,backwards))
Abhishek K Das
Abhishek K Das
3,446 Points
Abhishek K Das
Abhishek K Das
3,446 Points

I had misunderstood the task itself it seems, we had to just do item[::-1] in the first task