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Alvaro Sanmartin Cid
Python Web Development Techdegree Student 1,065 PointsProblem with slices
I need to return the first and last 4 items of the list, but I don't understand why it keeps saying that it returns the wrong values.
def first_4 (list):
return list[:4]
def first_and_last_4 (list):
return first_4(list).append(list[-4:])
2 Answers
Dave StSomeWhere
19,870 PointsI see two issues.
You are using append() which will append 1 object into the list - so you last 4 would be inserted a 1 entry list not the 4 individual values. You'll need to use extend() which merges lists.
You'll need to break out the slice steps (I don't understand why well enough to explain) because you just can return slice and extend values. So, create a variable for the first 4, then extend that list with the last 4 and then return you new variable. Your slicing value correct.
You should always run you code in the console/IDLE to verify and debug - only way to see what is happening.
Something like:
def slice_example(list):
new_list = list[:4] #you can use your function here if you want
last_4 = list[:-4]
new_list.extend(last_4)
return new_list