[29346] in Perl-Users-Digest
Perl-Users Digest, Issue: 590 Volume: 11
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Wed Jun 27 14:14:39 2007
Date: Wed, 27 Jun 2007 11:14:13 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Wed, 27 Jun 2007 Volume: 11 Number: 590
Today's topics:
skip first N lines when reading file <jiehuang001@gmail.com>
Re: skip first N lines when reading file <noreply@gunnar.cc>
Re: skip first N lines when reading file <peter@makholm.net>
Re: skip first N lines when reading file <wahab@chemie.uni-halle.de>
Re: skip first N lines when reading file <jiehuang001@gmail.com>
Re: strings with formatted characters in %ARGV <savagebeaste@yahoo.com>
Re: The Modernization of Emacs: terminology buffer and <borud-news@borud.no>
Re: The Modernization of Emacs: terminology buffer and <twisted0n3@gmail.com>
Re: The Modernization of Emacs: terminology buffer and <mkb@incubus.de>
Re: The Modernization of Emacs: terminology buffer and (Joel J. Adamson)
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Wed, 27 Jun 2007 08:59:22 -0700
From: Jie <jiehuang001@gmail.com>
Subject: skip first N lines when reading file
Message-Id: <1182959962.668605.163690@q75g2000hsh.googlegroups.com>
Hi,
can someone please let me know how to skip first N lines when reading
a file in perl? I know that I can write something like below, but too
much coding and computing is involved.
also, can someone please let me know if there is a master pdf file
that has all the perl documentation content. right now, from
perldoc.per.org i found it is divided into many many files..
======my code to skip first N lines======
$line = 0;
while(<IN>) {
if ($line <= N) {
} else {
do something
}
}
------------------------------
Date: Wed, 27 Jun 2007 18:34:00 +0200
From: Gunnar Hjalmarsson <noreply@gunnar.cc>
Subject: Re: skip first N lines when reading file
Message-Id: <5efi1bF38bqcgU1@mid.individual.net>
Jie wrote:
> can someone please let me know how to skip first N lines when reading
> a file in perl?
One way:
use Tie::File;
my $skip = 3;
tie my @file, 'Tie::File', 'myfile' or die $!;
print "$_\n" for @file[ $skip..$#file ];
untie @file;
--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl
------------------------------
Date: Wed, 27 Jun 2007 17:07:17 +0000
From: Peter Makholm <peter@makholm.net>
Subject: Re: skip first N lines when reading file
Message-Id: <87y7i5uy0q.fsf@makholm.net>
Jie <jiehuang001@gmail.com> writes:
> ======my code to skip first N lines======
>
> $line = 0;
> while(<IN>) {
> if ($line <= N) {
> } else {
> do something
> }
> }
My take:
while(<IN>) {
next if 1 .. N;
do something;
}
if N is a constant expression or else you have to use at little less
magic:
my $N = lines_to_skip();
while(<IN>) {
next if 1 .. $N==$.;
do something;
}
Read 'perldoc perlop' look for the 'Range Operators' section.
//Makholm
------------------------------
Date: Wed, 27 Jun 2007 19:15:02 +0200
From: Mirco Wahab <wahab@chemie.uni-halle.de>
Subject: Re: skip first N lines when reading file
Message-Id: <f5u5us$24ff$1@nserver.hrz.tu-freiberg.de>
Gunnar Hjalmarsson wrote:
> Jie wrote:
>> can someone please let me know how to skip first N lines when reading
>> a file in perl?
>
> One way:
>
> use Tie::File;
> my $skip = 3;
> tie my @file, 'Tie::File', 'myfile' or die $!;
> print "$_\n" for @file[ $skip..$#file ];
> untie @file;
This might be sometimes a good, sometimes a bad idea.
example: file w/110000 lines (4.xMB)
The tie-solution
...
use Tie::File;
my ($skip, $len) = (30, 0);
tie my @file, 'Tie::File', 'myfile.txt' or die $!; # invoke file
print $file[$skip], "\n"; # skip n lines, print this line (validity)
$len += length for @file[ $skip..$#file ]; # compute lentgh of remaining lines
print scalar @file, " => $len\n"; # output: length and number of lines
untie @file;
...
would need around 16 seconds to (user) complete (588/Linux/2.5GHz AthlonXP),
whereas the straight thing:
...
my ($skip, $len) = (30, 0);
open my $fh, '<', 'myfile.txt' or die $!; # invoke file
1 while $skip-- && <$fh>; # skip n lines
print scalar <$fh>, "\n"; # print this line (validity)
$len += (length)-1 while <$fh>; # compute lentgh of remaining lines
# (remove newline!)
print "$. => $len\n"; # output: length and number of lines
...
passes through in far below 0.15 (!) seconds on the same machine
(several runs checked)
Regards
M.
------------------------------
Date: Wed, 27 Jun 2007 10:58:41 -0700
From: Jie <jiehuang001@gmail.com>
Subject: Re: skip first N lines when reading file
Message-Id: <1182967121.916071.313450@q69g2000hsb.googlegroups.com>
Hi, Makholm:
Thank you so much!! "next if 1 .. N" works great!!
I am going to post another question here, regarding an "out of memory"
issue which has troubled me for a long while. Hope I can get it
resoved here.
Thank you again!!
Jie
------------------------------
Date: Wed, 27 Jun 2007 08:39:22 -0700
From: "Clenna Lumina" <savagebeaste@yahoo.com>
Subject: Re: strings with formatted characters in %ARGV
Message-Id: <5efelgF383a41U1@mid.individual.net>
Michele Dondi wrote:
> On Tue, 26 Jun 2007 14:12:55 -0700, "Clenna Lumina"
> <savagebeaste@yahoo.com> wrote:
>
>> Note, I noticed that if I passed the arguements without any quoting
>> (./foo.pl 1 2\n3) the "\" would get stripped (I'm guessing my the
>> shell - linux, bash) so perl only sees '1 2n3'... why does the slash
>> get
>
> Yes, it's the shell.
>
>> stripped?
>
> Because the shell does so. It has it's own backslash quoting, e.g. to
> quote a bare single quote. But it doesn't handle special charachters.
> We have to live with that.
I had some how forgot the shell handles foward slashes like that. It
seems youy can simply escape them too as an alternative to quoting
(./foo.pl 1 2\\n3), if one really wanted to.
--
CL
------------------------------
Date: 27 Jun 2007 15:09:34 +0200
From: Bjorn Borud <borud-news@borud.no>
Subject: Re: The Modernization of Emacs: terminology buffer and keybinding
Message-Id: <m3ir99wnld.fsf@borud.not>
["Kjetil S. Matheussen" <k.s.matheussen@notam02.no>]
|
| Things have probably changed a little, but the stuff in SISC isn't
| specific for scheme, although a schemish language is used in the book.
well, those are really two separate discussions: Scheme and whether
SICP is an important book or not.
-Bjørn
------------------------------
Date: Wed, 27 Jun 2007 14:43:02 -0000
From: Twisted <twisted0n3@gmail.com>
Subject: Re: The Modernization of Emacs: terminology buffer and keybinding
Message-Id: <1182955382.783515.167290@n60g2000hse.googlegroups.com>
On Jun 27, 8:26 am, g...@mail.ru (Timofei Shatrov) wrote:
> >For which you need an interpreter. Such as Ghostscript. Which is a
> >pain to install and a bigger one to configure, even on Windoze.
>
> Lie. Ghostscript works out of the box on Windows.
You're joking. First of all I am not a liar, and secondly, Ghostscript
and Ghostview are tricky to set up correctly. I know -- I've done it a
time or three. There's an arcane GUI configurator that isn't
exceptionally well designed, and once it's working it still wonks out
on maybe 1 in 10 .ps and .eps files you come across ... which is still
better than being able to view none of them, mind you. Nonetheless
there's a world of difference between the GS tools and say Adobe
Acrobat Reader in terms of setup and use; the latter you just run an
installer and then find a pdf to double-click; no other steps
necessary and it works every time. Of course, Adobe stuff is
proprietary, and acrord supports some types of evil DRM...
------------------------------
Date: Wed, 27 Jun 2007 18:05:38 +0200
From: Matthias Buelow <mkb@incubus.de>
Subject: Re: The Modernization of Emacs: terminology buffer and keybinding
Message-Id: <5efg6iF38nuukU1@mid.dfncis.de>
Bjorn Borud wrote:
> I was told by a lot of people I consider to be intelligent that this
> book would change how I think about writing software. it didn't. I
> didn't really know what to expect, but after reading it I did feel
> that its importance was greatly exaggerated.
I think it's basically a course book, for some CS courses at MIT that it
was originally used with, and that's it. It's not superb but ok, as far
as "lecture notes" go, a bit pretentious and a bit idiosyncratic,
probably due to being targeted mainly at students visiting a particular
course of lectures. I don't think it's supposed to be a general "how to
learn good programming"-style book although I don't think you've wasted
time reading it.
F'up-to: c.l.lisp.
------------------------------
Date: Wed, 27 Jun 2007 13:32:45 -0400
From: jadamson@partners.org (Joel J. Adamson)
Subject: Re: The Modernization of Emacs: terminology buffer and keybinding
Message-Id: <87odj1joaq.fsf@W0053328.mgh.harvard.edu>
Twisted <twisted0n3@gmail.com> writes:
> On Jun 27, 8:26 am, g...@mail.ru (Timofei Shatrov) wrote:
>> >For which you need an interpreter. Such as Ghostscript. Which is a
>> >pain to install and a bigger one to configure, even on Windoze.
>>
>> Lie. Ghostscript works out of the box on Windows.
>
> You're joking. First of all I am not a liar, and secondly, Ghostscript
> and Ghostview are tricky to set up correctly. I know -- I've done it a
> time or three. There's an arcane GUI configurator that isn't
> exceptionally well designed, and once it's working it still wonks out
> on maybe 1 in 10 .ps and .eps files you come across ...
It's become clear that you have a different conception of what
consitutes "working" software.
> better than being able to view none of them, mind you. Nonetheless
> there's a world of difference between the GS tools and say Adobe
> Acrobat Reader in terms of setup and use; the latter you just run an
> installer and then find a pdf to double-click; no other steps
> necessary and it works every time. Of course, Adobe stuff is
> proprietary, and acrord supports some types of evil DRM...
It's also become clear that you have a different conception of what
constitutes using a computer.
Joel
--
Joel J. Adamson
Biostatistician
Pediatric Psychopharmacology Research Unit
Massachusetts General Hospital
Boston, MA 02114
(617) 643-1432
(303) 880-3109
*Joel's guide to sending attachments:
1. put all the files you want to send in a folder and archive the
folder using tar, then compress it with gzip or bzip2
2. please send me .pdf, .html, or text in place of Word documents:
http://www.gnu.org/philosophy/sylvester-response.html
*Did you know there's a FREE alternative to using word processors?
http://www.edafe.org/latex/
http://en.wikipedia.org/wiki/LaTeX
http://nitens.org/taraborelli/latex
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
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Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
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------------------------------
End of Perl-Users Digest V11 Issue 590
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