Converting certain index values in list to int

Question

I have searched for a solution to this, but I have not been able to find one, weirdly.

I am opening a file with the following contents in it.

Alex,10,0,6,3,7,4
Bob, 6,3,7,2,1,8

I want to convert all the values in score_list from 1-4 index value to an integer. I have tried to do so with this following but it just doesn't work.

    score_list = []
    def opening_file():
         counter = 0
         with open('scores.txt', newline='') as infile:
             reader = csv.reader(infile)
             for row in reader:
                score_list.append(row[0:5])

             counter = 0
             while counter != 5:
               counter +=1
               row[counter] = int(row[counter])
             print (score_list)

    opening_file()

but it doesn't work and just produces

[['Alex', '10', '0', '6', '3'], ['Bob', ' 6', '3', '7', '2']]

instead of [['Alex', 10, 0, 6, 3], ['Bob', 6, 3, 7, 2]]

Kasravnd · Accepted Answer · 2016-02-16 21:07:02Z

2

You are converting the items within row which is just a throwaway variable. Also you don't need to that redundant works, you can simply unpack your row to name and scores parts and use a list comprehension in order to convert the digits to integer.

with open('scores.txt', newline='') as infile:
    reader = csv.reader(infile)
    for row in reader:
        name, *scores = row
        score_list.append([name] + [int(i) for i in scores])

edited Feb 16, 2016 at 21:07

answered Feb 16, 2016 at 20:59

Kasravnd

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5 Comments

Tamas Hegedus Over a year ago

I think you cannot concatenate arbitrary iterables to a list

Kasravnd Over a year ago

@TamasHegedus Sorry I didn't got you. What you mean by arbitrary iterables?

Tamas Hegedus Over a year ago

I mean a python 3.x map object: [name]+map(int, scores)

Kasravnd Over a year ago

@TamasHegedus Yeah, Indeed. Thanks for reminding that I just changed it.

Tamas Hegedus Over a year ago

I like the use of the extended unpacking here, +1

Blckknght · Accepted Answer · 2016-02-16 20:59:42Z

1

Your while loop transforming the values in row happens too late. Each row's values have already been copied (by a slice operation) into a new list which has been appended to score_list. And you only run the loop on the last row anyway (assuming your indentation in the question is correct).

Try something like this:

with open('scores.txt', newline='') as infile:
    reader = csv.reader(infile)
    for row in reader:
        for i in range(1,5):
            row[i] = int(row[i])
        score_list.append(row[0:5])

I'm using a for loop on a range, rather than a while loop, just because it's more convenient (a while loop version could work just fine, it just requires more lines). The key thing is to change row inside the loop on reader and before we slice the row to append to score_list.

answered Feb 16, 2016 at 20:59

Blckknght

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1 Comment

Gabriel A. Over a year ago

Thanks a lot for that. I found all the answers helpful but I found this one in particular because you did remember to add in the code that only appends row[0:5].

Tamas Hegedus · Accepted Answer · 2016-02-16 21:01:17Z

1

First of all, the code converts items in the row array, but you print the score_list array. Second, as it alters the row variable outside the reader for loop, it only alters the last row. You could do something like this:

import csv

def opening_file():
  with open('scores.txt', newline='') as infile:
    return [[row[0]] + [int(x) for x in row[1:]] for row in csv.reader(infile)]
score_list = opening_file()
print(str(score_list))

answered Feb 16, 2016 at 21:01

Tamas Hegedus

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