Problem with "list assignment index out of range" Python

Question

I should replace the last element of a tuple in a list of tuples with and object given as input and I tried to write this code but I got a "list assignment index out of range" error at line 4. How should I fix it?

def replaceLast (tupleList, object):
    for i, tup in enumerate(tupleList):
        lis = list(tup)
        lis[-1] = object
        tupleList[i] = tuple(lis)
    return tupleList

lT=[(1,),(2,3),(),(7,3)]
replaceLast(lT,11) #=> [(11,), (2, 11), (11,), (7, 11)] -> this should be the result

Please share the entire error message, as well as a minimal reproducible example. Also, variable and function names should follow the lower_case_with_underscores style. — AMC
– AMC, Commented Feb 16, 2020 at 2:15

Daniel · Accepted Answer · 2020-02-15 18:03:25Z

3

The problem is the empty tuple in your list lT, which does not have a last element, therefore you cannot access it with lst[-1].

Instead of changing lists, create new ones:

def replace_last(tuples, object):
    return [
        tup[:-1] + (object, )
        for tup in tuples
    ]

edited Feb 15, 2020 at 18:03

answered Feb 15, 2020 at 18:01

Daniel

42.9k4 gold badges57 silver badges82 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

sophros Over a year ago

Could you also please add an information why the error happened?

kederrac · Accepted Answer · 2020-02-15 18:06:10Z

1

your issue is generated when you have empty tuple, then your variable lst will be an empty list so will not make sense to use lst[-1], this will generate your error, a simple fix will be to check if is an empty list:

if lst:
    lst[-1] = object
else:
    lst.append(object)

answered Feb 15, 2020 at 18:06

kederrac

17.4k6 gold badges36 silver badges58 bronze badges

Collectives™ on Stack Overflow

Problem with "list assignment index out of range" Python

2 Answers 2

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related