Sorry for replying to the wrong thread. This previous mail was an answer to
http://python.6.x6.nabble.com/Novice-Question-on-File-seek-and-tell-methods-td5021174.html On Mon, Jun 17, 2013 at 4:27 PM, Saurabh Hirani <saurabh.hir...@gmail.com>wrote: > The problem is that when you do "for line in f" you are using Python's > iterators and they are not rewindable i.e. "for line in f" gives call the > next() function but there is no way to go back when you use iterators. You > can solve your problem with the following snippet of code > > > #!/usr/bin/env python > > import re > import sys > > # not doing input validation > # call program as: python prog.py start_keyword stop_keyword file_to_read > startat = sys.argv[1] > stopat = sys.argv[2] > inputfile = sys.argv[3] > > re_startat = re.compile(r'^%s$' % (startat)) > re_stopat = re.compile(r'^%s$' % (stopat)) > pattern = re_startat > > with open(inputfile) as f: > line = f.readline() > inrange = False > while line: > match = re.search(pattern, line) > # if the pattern matches > if (match): > # and we are not in range of startat - stopat > if (not inrange): > # get in range and change the pattern > inrange = True > pattern = re_stopat > else: > # we are in the range => stopat pattern matched > # print line and exit > print line > break > if (inrange): > # we are in range + stopat pattern not matched > # keep on printing > print line > line = f.readline() > > It does look prettier in vim on a black screen though :) > > The idea is you are "in range" if you have matched your first keyword and > till you stay in the range you keep on printing. When you find your next > keyword, you are "out of the range" and you exit. > > Hope that helps. > > -- > regards, > Saurabh. > http://curiosityhealsthecat.blogspot.in/ > > > > On Mon, Jun 17, 2013 at 3:30 PM, <bangpypers-requ...@python.org> wrote: > >> Send BangPypers mailing list submissions to >> bangpypers@python.org >> >> To subscribe or unsubscribe via the World Wide Web, visit >> http://mail.python.org/mailman/listinfo/bangpypers >> or, via email, send a message with subject or body 'help' to >> bangpypers-requ...@python.org >> >> You can reach the person managing the list at >> bangpypers-ow...@python.org >> >> When replying, please edit your Subject line so it is more specific >> than "Re: Contents of BangPypers digest..." >> >> >> Today's Topics: >> >> 1. Re: [Novice] Question on File seek and tell methods (Vishal) >> >> >> ---------------------------------------------------------------------- >> >> Message: 1 >> Date: Mon, 17 Jun 2013 01:22:23 +0530 >> From: Vishal <vsapr...@gmail.com> >> To: Bangalore Python Users Group - India <bangpypers@python.org> >> Subject: Re: [BangPypers] [Novice] Question on File seek and tell >> methods >> Message-ID: >> <CACPguY-jfVNb85_==Mvih0-Chj1Ws-rA=- >> drgbyykgjwp1j...@mail.gmail.com> >> Content-Type: text/plain; charset=UTF-8 >> >> Hi, >> >> If the file you are talking about is not too big...i mean has less than >> say >> 50,000 lines, then the simplest would be to do: >> >> with open('fileName') as fin: >> lines = fin.readlines() >> >> printStuff = False >> for line in lines: >> if 'start_keyword' in line: >> printStuff = True >> print line >> >> elif 'stop_keyword' in line: >> print line >> break >> >> elif printStuff: >> print line >> >> Hope this helps, >> Vishal Sapre >> >> >> >> Thanks and best regards, >> Vishal Sapre >> >> --- >> "Life is 10% how you make it, and 90% how you take it" >> "????? ?????, ????? ????? (Benefit for most people, Happiness for most >> people.)" >> --- >> Please DONT print this email, unless you really need to. Save Energy & >> Paper. Save the Earth. >> >> >> On Thu, Jun 13, 2013 at 1:18 AM, davidsnt <david...@gmail.com> wrote: >> >> > Group, >> > >> > I need a little help in using the file seek and tell methods, I have a >> file >> > with n lines, in which I have to find out the line which starts from a >> > particular keyword and print all the lines until I find next matching >> > keyword. >> > >> > I did a work around using seek and tell, I used regex as well. I opened >> the >> > file, read line by line in a for loop, and checked each line for the >> > keyword used tell() to get the position and the seek() to move my cursor >> > and tried to print next lines until I get the next matching keyword but >> I >> > failed can you help me here. >> > >> > Example test file >> > >> > test.log >> > >> > Bangalore >> > Hyderabad >> > Chennai >> > Mumbai >> > Tennis >> > Cricket >> > Poker >> > Angry Birds >> > Cricket >> > Mumbai >> > Chennai >> > >> > >> > I want to read and print from Chennai to Angry Birds >> > >> > import sys,re >> > >> > f = open('test.log', 'r') >> > >> > for line in f: >> > match = re.search('^Chennai', line) >> > if(match): >> > f.seek(f.tell(), 0) >> > <I am missing out the logic from here> >> > >> > >> > Thanks, >> > David >> > _______________________________________________ >> > BangPypers mailing list >> > BangPypers@python.org >> > http://mail.python.org/mailman/listinfo/bangpypers >> > >> >> >> ------------------------------ >> >> Subject: Digest Footer >> >> _______________________________________________ >> BangPypers mailing list >> BangPypers@python.org >> http://mail.python.org/mailman/listinfo/bangpypers >> >> >> ------------------------------ >> >> End of BangPypers Digest, Vol 70, Issue 17 >> ****************************************** >> > > > > -- > Saurabh > -- Saurabh _______________________________________________ BangPypers mailing list BangPypers@python.org http://mail.python.org/mailman/listinfo/bangpypers
