>>> lst = ['1','2','3'] >>> lst[:2] + ['data'] + lst[2:] ['1', '2', 'data', '3'] >>>
>>> lst = ['1','2','3'] >>> lst[:2] + ['data'] + lst[2:] ['1', '2', 'data', '3'] >>>
with open('in.csv') as infile, open('out.csv','w') as outfile: for line in infile: lst = line.strip().split(',') tmp = lst[:7] + ['mydata'] + lst[7:] outfile.write(','.join(tmp) +'\n')