CODEWITHSUNDEEP
pythonlistpython-3.xpython-3.5
user6246171
user6246171

Reputation:

How do you reverse a list at a given value?

I'm trying to design a code that will reverse a given list at the index of a given value. The rest of the list beyond the value will be printed in correct order, but I can't seem to complete it.

This is the code I have so far.

def reverse(my_list, value):

    lst = []
    lst2 = []

    for x in range(my_list[0], my_list[value]):
        x = my_list[x]
        lst2.append(x)

    for i in range(len(lst2)-1, -1, -1):
        x = lst2[i]
        lst.append(x)

    for x in range(my_list[value], len(my_list)):
        x = my_list[x]
        lst.append(x)

    print(lst)

If the input is this.

reverse([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 5)

The output should be.

[5, 4, 3, 2, 1, 6, 7, 8, 9, 10]

But instead the output is this.

[6, 5, 4, 3, 2, 7, 8, 9, 10]

Can anyone help me to determine how to get the needed output?

Upvotes: 2

Views: 360

Answers (2)

Serenity
Serenity

Reputation: 36635

Indexes in first and third cycles are wrong, you have to iterate through indexes not values. Write like here:

def reverse(my_list, value):

    lst = []
    lst2 = []

    for x in range(0, value):
        x = my_list[x]
        lst2.append(x)

    for i in range(len(lst2)-1, -1, -1):
        x = lst2[i]
        lst.append(x)

    for x in range(value, len(my_list)):
        x = my_list[x]
        lst.append(x)

    print(lst)

reverse([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 5)

output: [5, 4, 3, 2, 1, 6, 7, 8, 9, 10]

Upvotes: 0

Mureinik
Mureinik

Reputation: 311063

It would be much easier to implement with slicing:

def reverse(my_list, value):
    return my_list[:value][::-1] + my_list[value::]

Upvotes: 2

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