Sum of different CSV columns in python

Question

I am quite new to Python and therefore this might seem easy but I am really stuck here.

I have a CSV file with values in a [525599 x 74] matrix. For each column of the 74 columns I would like to have the total sum of all 525599 values saved in one list.

I could not figure out the right way to iterate over each column and save the sum of each column in a list.

this can be done very simply with pandas (you should be able to read the docs) — chris, Dec 18 '18 at 11:03
duplicate: https://stackoverflow.com/questions/37602344/sum-each-column-of-csv-file — Jean-François Fabre, Dec 18 '18 at 11:14

score 1 · Answer 1 · answered Dec 18 '18 at 11:05

Why don't you :

create a columnTotal integer array (one index for each column).
read the file line by line, per line:
- Split the line using the comma as separator
- Convert the splitted string parts to integers
- Add the value of each column to the columnTotal array's colum index.

Fred · Answer 2 · 2018-12-18T11:17:16.550

0

Since you're new to python I won't use any fancy libraries like pandas or numpy. But you should definitely check those out some time

import csv

reader = csv.reader(open('your_csv.csv', 'r'))
sums = [0] * 74
for row in reader:
    for i, element in enumerate(row):
        sums[i] += int(element)
print(sums)

edited Dec 18 '18 at 11:17

answered Dec 18 '18 at 11:04

Fred

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this just doesn't work. csv file contains strings, you have to convert to float / int first. And hardcoding the list at start is very bad practice. – Jean-François Fabre Dec 18 '18 at 11:14
Yeah I missed the conversion. Just edited it. Now... Do we really care about good convention when the guy is just learning Python? I just wanted to make it simple for the guy. If I cared about it I would probably just use pandas – Fred Dec 18 '18 at 11:19

Sum of different CSV columns in python

2 Answers2