How to find specific rows in csv document in python -

what i'm trying read csv document , find values in sn column > 20 , make new file rows sn > 20.

i know need do:

1. read original file
2. open new file
3. iterate on rows of original file

what i've been able find rows have value of sn > 20

import csv import os  os.chdir("c:\users\robert\documents\qwe")  open("gdweights_feh_robert_cmr.csv",'rb') f:     reader = csv.reader(f, delimiter= ',')     zerovar = 0     row in reader:         if zerovar==0:             zerovar = zerovar + 1         else:             sn = row [11]             zerovar = zerovar + 1             x = float(sn)             if x > 20:                 print x 

so question how take rows sn > 20 , turn new file?

save data in list, write list file.

import csv import os  os.chdir(r"c:\users\robert\documents\qwe")  output_ary = [] open("gdweights_feh_robert_cmr.csv",'rb') f:     reader = csv.reader(f, delimiter= ',')     zerovar = 0     row in reader:         if zerovar==0:             zerovar = zerovar + 1         else:             sn = row [11]             zerovar = zerovar + 1             x = float(sn)             if x > 20:                 print x                 output_ary.append(row)  open("output.csv",'w') f2:     row in output_ary:         item in row:             f2.write(item + ",")