How to use python to add a column to a csv file?

[ronparker]

Hello all!
I have a csv file which is usually has between 100 and 200 columns. I have a new column of data that I want to add to the csv file. I know if you open the file as "A" it will append the file, but I only know how to use it to add new rows to the document. not new columns.
Right now this code will write three columns of data:

myFile= open( "CC4.csv", "wb" )
wtr= csv.writer( myFile )
for blanka,s,q in zip(blanka,s,q):
    wtr.writerow([blanka,s,q])
myFile.close()
 

Now assuming I have an array called "data" and I don't know how many columns are already written in the file, how can I add this new column to the file?

Thank you,
Ron Parker

[bvdet]

Read the existing CSV file. Create a new array of data and append the new columns to each row. Then write the new array to disc. An example:

import csv
 
f = open('csv2.txt')
data = [item for item in csv.reader(f)]
f.close()
 
new_column = ["Col 1", "Line 1", "Line 2"]
 
new_data = []
 
for i, item in enumerate(data):
    try:
        item.append(new_column[i])
    except IndexError, e:
        item.append("placeholder")
    new_data.append(item)
 
f = open('csv2B.txt', 'w')
csv.writer(f).writerows(new_data)
f.close()