CODEWITHSUNDEEP
pythonlist
Richard Summers
Richard Summers

Reputation: 143

Python - replacing specific numbers in a list

I have scores from a questionnaire:

list= [1, 2, 2, 4, 1, 4, 1, 3, 2, 2, 2, 1, 1, 1, 4, 3, 4, 2, 1, 1, 1, 1, 1, 2, 2, 2, 4, 1, 4, 1, 2, 4, 4, 4, 4, 4, 2, 3, 2, 3, 3, 3]

Certain questions need to be reverse-scored. "Rscores" is the list of indexes that need to be reverse-scored, this means that for those scores, if it's 1, then it needs to be replaced with a 4 and if it's a 2, it needs to be replaced with a 3.

Rscores = [1, 6, 11, 16, 21, 28, 33, 38, 43, 49, 57, 8, 46, 2, 7, 12, 17, 22, 25, 35, 40]

I have tried this, and many variations of it, but it doesn't work:

for Rscores in list:
    if list[Rscores] == 1:
        list[Rscores] = 4
    elif list[Rscores] == 2:
        list[Rscores] = 3
    elif list[Rscores] == 3:
        list[Rscores] = 2
    elif list[Rscores] == 4:
        list[Rscores] = 1

If anyone can help, I would be very grateful. Thanks in advance

Upvotes: 0

Views: 313

Answers (3)

Chetan Mahajan
Chetan Mahajan

Reputation: 369

it;s working 

list= [1, 2, 2, 4, 1, 4, 1, 3, 2, 2, 2, 1, 1, 1, 4, 3, 4, 2, 1, 1, 1, 1, 1, 2, 2, 2, 4, 1, 4, 1, 2, 4, 4, 4, 4, 4, 2, 3, 2, 3, 3, 3]

for n, i in enumerate(list):
    if i == 1:
        list[n] = 4
    if i == 2:
        list[n] = 3
    if i == 3:
        list[n] = 2
    if i == 4:
        list[n] = 1
print(list)

Hope it's help full

enter image description here

Upvotes: 0

rigsby
rigsby

Reputation: 792

L = [1, 2, 2, 4, 1, 4, 1, 3, 2, 2, 2, 1, 1, 1, 4, 3, 4, 2, 1, 1, 1, 1, 1, 2, 2, 2, 4, 1, 4, 1, 2, 4, 4, 4, 4, 4, 2, 3, 2, 3, 3, 3]
Rscores = [1, 6, 11, 16, 21, 28, 33, 38, 43, 49, 57, 8, 46, 2, 7, 12, 17, 22, 25, 35, 40]

def reverseScore(score):
    if score == 1:
        return 4
    elif score == 2:
        return 3
    elif score == 3:
        return 2
    elif score == 4:
        return 1

def rscoredList(L):
    for idx in Rscores:
        if idx < len(L):
            L[idx] = reverseScore(L[idx])
    return L

L = rscoredList(L)

I think a problem in the example you listed is that you have indices in your Rscores that are outside the range of your list. (57 is listed as a to be reversed index tho it can't be because len(L)==42.)

Upvotes: 0

holdenweb
holdenweb

Reputation: 37043

This creates a new list, with the necessary scores rectified.

lst= [1, 2, 2, 4, 1, 4, 1, 3, 2, 2, 2, 1, 1, 1, 4,
      3, 4, 2, 1, 1, 1, 1, 1, 2, 2, 2, 4, 1, 4, 1,
      2, 4, 4, 4, 4, 4, 2, 3, 2, 3, 3, 3]

Rscores = [1, 6, 11, 16, 21, 28, 33, 38, 43, 49, 57,
           8, 46, 2, 7, 12, 17, 22, 25, 35, 40]

rectified_scores = [5-x if i in Rscores else x for i, x in enumerate(lst)]

enumerate yields a sequence of pairs (i, x), where i is the element index and x is its value. 5-x if i in Rscores else x is the score for a standard index, and the inverse of the score for indexes in the Rscores list.

I renamed your list to avoid "shadowing" the name of a Python type. Your code would probably run marginally faster if Rscores were a set, but it's not screaming to be optimised.

Upvotes: 1

Related Questions