When I tried to do some calculation between two columns (like division), I get an error: column_ratio[x]=(float(column1[y]))/(float(column2[z])) TypeError: tuple indices must be integers, not str. Could someone help me to solve this problem?

from itertools import izip_longest
import csv
with open(r"C:\Users\a.txt", 'rb') as csv1,\open(r"C:\Users\b.txt", 'rb') as csv2, \open(r"C:\Users\c.txt", 'rb') as csv3, \open(r"C:\Users\out.txt", 'w') as out:spam1 = csv.reader(csv1, delimiter=',')spam2 = csv.reader(csv2, delimiter=',')spam3= csv.reader(csv3, delimiter=',')column1=list(izip_longest(*spam1))[-1]column2=list(izip_longest(*spam2))[-1]column3=list(izip_longest(*spam3))[-1]column_ratio=[]for x,y,z in izip_longest(column_ratio, column1, column2):column_ratio[x]=(float(column1[y]))/(float(column2[z]))for i,j,m,n,x in izip_longest(spam1,column1, column2, column3, column_ratio):out.write(','.join(i)+','+j+','+m+','+n+','+x+'\n')

When you parse with the CSV reader, it has no way of knowing that the data should be an integer, a float, a string, etc. All comma-delimited data is parsed as a string, and it's up to you to convert it to the right type. You'll need to coerce the string to an integer to use it as an index.

Take the following CSV:

Index One, Index Two, Index Three
0,1,2

When parsing it:

x, y, z = reader.next()  # ['0', '1', '2']
print my_tuple[x]  # TypeError: tuple indices must be integers, not str
print my_tuple[int(x)]  # Expected result