[FEEDBACK] Is this script efficient...is there a better way?

Bob X bobx at linuxmail.org
Thu Sep 12 03:20:00 CEST 2002


Steve Holden wrote:
<snip>
>>#!/usr/local/bin/python -w
>>
>># import the needed libs
>>import sys, string
>>
>># make sure the command line arguments are there
>>if len(sys.argv) < 3:
>>     print "usage: fread.py [log file] [hit file]"
>>     sys.exit(1)
>>
> 
> Unless the return is important, you'll find
> 
>     sys.exit("usage: fread.py [log file] [hit file]")
> 
> more convenient.
> 
> 
>># open the files with some error checking
>>try:
>>     inFile = open(sys.argv[1],"r")
>>except IOError:
>>     print "Cannot open log file!\n"
>>     sys.exit(1)
>>
>>try:
>>     outFile = open(sys.argv[2],"w")
>>except IOError:
>>     print "Cannot open hits file!\n"
>>     sys.exit(1)
>>
> 
> Your error checking is exemplary. Normally I'm happy to have a Python
> exception explain the error condition, but of course your explicit messages
> are great.
> 
> 
>># build list of keywords
>>kw = [ "some", "words" ]
>>
>># loop through the list and print the lines to a file
>>for line in inFile.readlines():
>>     for badword in kw:
>>         if line.find(badword) > -1:
>>             result = '%s %s' % (badword, line)
>>             print result            # Print the result
>>             outFile.write(result)   # Write the result
>>
> 
> If you only wanted to know the lines that match at least one of the words
> you could follow the write() with a "break", since there's no need to
> continue the loop then.
> 
> Also, the "print" looks like a debugging statement.
> 
> 
>># close the files
>>inFile.close()
>>outFile.close()
>>
>># let me know when it's done
>>print "Finished processing file..."
>>
> 
> Highly commendable. Another approach would be to build a regular expression
> from the keywords list and search for the r.e. in each line. The following
> code is untested...
> 
> kw = ["some", "words"]
> kwpat = "|".join(kw)
> pat = re.compile(kwpat)
> for line in inFile.readlines():
>     if pat.search(line):
>         outFile.write(line)
> 
> for example.
> 
> regards
> -----------------------------------------------------------------------
> Steve Holden                                  http://www.holdenweb.com/
> Python Web Programming                 http://pydish.holdenweb.com/pwp/
> Previous .sig file retired to                    www.homeforoldsigs.com
> -----------------------------------------------------------------------
> 
> 
> 
Thank you very much...as a follow up:

#1 Can I use the same sys.exit("message here") on the IO errors as well?
#2 For the "print looks like a debugging statement"...how would it be 
done different...in the context of my script and not a total re-write?
#3 I will test your shorter one as I have stayed away from RE till now.
#4 On your shorter one should xreadlines still be done for memory sake?

Thanks!

Bob




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