[Tutor] Text Processing Query

[Mitya Sirenef]

On 03/14/2013 07:28 AM, taserian wrote:
> Since the identifier and the  item that you want to keep are on different lines, you'll need to set 
a "flag".
 >
 > with open(filename) as file:
 >
 > scanfile=file.readlines()
 >
 > flag = 0
 >
 > for line in scanfile:
 >
 > if line[0:6]=='COMPND' and 'FAB FRAGMENT' in line: flag = 1
 >
 > elif line[0:6]=='COMPND' and 'CHAIN' in line and flag = 1:
 >
 > print line
 >
 > flag = 0
 >
 >
 > Notice that the flag is set to 1 only on "FAB FRAGMENT", and it's 
reset to 0 after the next "CHAIN" line that follows the "FAB FRAGMENT" line.


I would simplify this a bit as follows:

flag = 0

for line in scanfile:
     if line.strip():
         if 'FAB FRAGMENT' in line:
             flag = 1
         elif flag:
             print line
             flag = 0

This assumes CHAIN line always follows MOLECULE line (otherwise elif
needs to check for CHAIN as well), it also ignores blank lines.

  -m



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