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Python Python Collections (2016, retired 2019) Slices Slice Functions

Posted by Suresh N
Suresh N
743 Points

Code working in Workspaces, but throwing error in Challenge window.Need help.

Code working in Workspaces, but throwing error in Challenge window.Need help.

slices.py 
def first_4(items):
    return items[0:4]

def first_and_last_4(items):
    slice1=items[0:4]
    slice2=items[-1:-5:-1]
    slice1.extend(slice2)
    return slice1

3 Answers

Dave StSomeWhere
Dave StSomeWhere
19,870 Points
Dave StSomeWhere
Dave StSomeWhere
19,870 Points

While you think your code is working, it is not producing the expected results.

The challenge is asking for you to return the first 4 and last 4 of a list - it doesn't say to reverse the the order of the last 4 (which your code produces) - I agree that is the last 4 and they really didn't specify an order but you're a step ahead and the challenge only accepts the last 4 in normal order.

Please adjust your slice2 to get the last 4 in the original order and you should be good to go...

You seem to have a good handle on slices so shouldn't be a problem, just ask if more info needed.

Suresh N
Suresh N
743 Points
Suresh N
Suresh N
743 Points

Thanks Dave. I changed the code as per your comments. Still am unable to get through in challenge window. Its working well in Workspaces. def first_4(items): return items[0:4]

def first_and_last_4(items): slice1=items[0:4] slice2=items[-1:-5:-1] slice2.sort() slice1.extend(slice2) return slice1

Dave StSomeWhere
Dave StSomeWhere
19,870 Points
Dave StSomeWhere
Dave StSomeWhere
19,870 Points

We can't use sort() since there doesn't have to be any specific order of the elements.

Now, you can reverse slice2 again instead of the sort but for this challenge it is much simpler.

Remember that you can control the start, stop and step of the slice. Hint you only need 1 of the three.

Check out this SO Answer for a pretty good explanation.

Does that help

Suresh N
Suresh N
743 Points
Suresh N
Suresh N
743 Points

Oh..got it. I am through now. Thank you very much for the hint.Appreciate it.