How to extract specific columns from a space separated file in Python? -

i'm trying process file protein data bank separated spaces (not \t). have .txt file , want extract specific rows and, rows, want extract few columns.

i need in python. tried first command line , used awk command no problem, have no idea of how same in python.

here extract of file:

 [...] seqres   6 b   80  ala leu ser ile lys lys ala gln thr pro gln gln trp           seqres   7 b   80  lys pro                                                       helix    1   1 thr   68  ser   81  1                                  14     helix    2   2 cys   97  leu  110  1                                  14     helix    3   3 asn  122  ser  133  1                                  12     [...] 

for example, i'd take 'helix' rows , 4th, 6th, 7th , 9th columns. started reading file line line loop , extracted rows starting 'helix'... , that's all.

edit: code have right now, print doesn't work properly, prints first line of each block (helix sheet , dbref)

#!/usr/bin/python import sys  line in open(sys.argv[1]):  if 'helix' in line:    helix = line.split()  elif 'sheet'in line:    sheet = line.split()  elif 'dbref' in line:    dbref = line.split()  print (helix), (sheet), (dbref) 

if have extracted line, can split using line.split(). give list, of can extract elements need:

>>> test='helix 2 2 cys 97' >>> test.split() ['helix', '2', '2', 'cys', 'a', '97'] >>> test.split()[3] 'cys'