[29816] in Perl-Users-Digest
Perl-Users Digest, Issue: 1059 Volume: 11
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Sat Nov 24 09:09:39 2007
Date: Sat, 24 Nov 2007 06:09:05 -0800 (PST)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Sat, 24 Nov 2007 Volume: 11 Number: 1059
Today's topics:
Re: A little help on perl hashes.. <nobull67@gmail.com>
Re: How to get the string Cartesian Products of 2 list <rvtol+news@isolution.nl>
Re: How to get the string Cartesian Products of 2 list xueweizhong@gmail.com
Re: How to get the string Cartesian Products of 2 list <bik.mido@tiscalinet.it>
Re: How to get the string Cartesian Products of 2 list <bik.mido@tiscalinet.it>
Re: How to get the string Cartesian Products of 2 list <bik.mido@tiscalinet.it>
Re: How to get the string Cartesian Products of 2 list xueweizhong@gmail.com
Re: searching for a pattern for multiple matches <rvtol+news@isolution.nl>
Re: SvUOK always fails on 64bit platform <sisyphus359@gmail.com>
Re: SvUOK always fails on 64bit platform <rvtol+news@isolution.nl>
union of 1 and 0 strings <avilella@gmail.com>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Sat, 24 Nov 2007 03:31:40 -0800 (PST)
From: Brian McCauley <nobull67@gmail.com>
Subject: Re: A little help on perl hashes..
Message-Id: <ee0dee28-33ca-4283-88bf-520a5170c3f2@s12g2000prg.googlegroups.com>
On Nov 23, 3:31 pm, nolo contendere <simon.c...@fmr.com> wrote:
>
> use strict; use warnings;
> use Data::Dumper;
>
> my %ids;
Good start.
>
> while ( <DATA> ) {
> next if /^\s*$/;
> chomp;
> my ( $userid, $uid, $mid ) = split;
> $ids{$uid} = { userid => $userid,
> mid => $mid,
> managerid => '' };
>
> }
I tend to follow the rule "always use the most natural representation
of things unless there is a reason to do otherwise". (It's one of my
top-five rules of programming).
In this case the "natural representation" of a hash not (yet) having a
managerid entry would be for it not to have a managerid entry.
>
> my $itr = 0;
You never use $itr
> for my $key ( keys %ids ) {
Since you never use $key except to look up $ids{$key} it would be more
efficient to loop over the values directly.
> my $managerid;
You are declaring this in the wrong scope.
> my $mid = $ids{$key}{mid};
>
> # find userid where uid = this $mid
> if ( exists $ids{$mid} ) {
There's nothing wrong with using exists() here but it is redundant
since we know that %ids will contain no false values.
> $managerid = lookup_userid( $mid );
This is where you should have declared $managerid (but since you only
use it once it's maybe not worth it at all).
> $ids{$key}{managerid} = $managerid;
> }
>
> }
>
> for my $uid ( keys %ids ) {
> unless ( $ids{$uid}{managerid} ) { $ids{$uid}{managerid} =
> $ids{$uid}{userid}; };
More simply
$ids{$uid}{managerid} ||= $ids{$uid}{userid};
However it would probably make sense to distinguish in some way
entries with no mid from those with an invalid mid.
> print "$ids{$uid}{userid}\t$ids{$uid}{managerid}\n";
>
> }
>
> #=========
> # subs
> #=========
>
> sub lookup_userid {
> my ( $mid ) = @_;
> return $ids{$mid}{userid};
>
> }
This function is probably too small to be worth it. Particularly given
the global variable.
The reasoning goes like this
Accessors - good
Global variables - bad
More complexity - bad
Nett gain - negative
------------------------------
Date: Sat, 24 Nov 2007 13:53:07 +0100
From: "Dr.Ruud" <rvtol+news@isolution.nl>
Subject: Re: How to get the string Cartesian Products of 2 list
Message-Id: <fi9ajf.1k0.1@news.isolution.nl>
Dr.Ruud schreef:
> Ted Zlatanov schreef:
>
>> local $" = ','; # List separator
>> print glob "{@{['a'..'c']}}{@{[1..3]}}\n";
>
> Command line version:
>
> perl -wle '
> $"=",";
> print for glob "{@{[ q{a}..q{c} ]}}{@{[ 1..3 ]}}"
> '
Others:
perl -le'
sub c{local $"=","; "{@_}"}
print for glob c("a".."c").c(1..3)
'
perl -le'
sub c{"{". join(",", @_) ."}"}
print for glob c("a".."c").c(1..3)
'
--
Affijn, Ruud
"Gewoon is een tijger."
------------------------------
Date: Sat, 24 Nov 2007 05:26:24 -0800 (PST)
From: xueweizhong@gmail.com
Subject: Re: How to get the string Cartesian Products of 2 list
Message-Id: <eac7689c-11ab-40c6-9ac6-f6751b5c8270@i12g2000prf.googlegroups.com>
> >> local $" = ','; # List separator
> >> print glob "{@{['a'..'c']}}{@{[1..3]}}\n";
Is this difference below a language feature or bug?
>perl -e 'local $" = ","; print join ",", <a{@{[q{001}..q{064}]}}>'
a001,a002,a003,a004,a005,a006,a007,a008,a009,a010,a011,a012,a013,a014,a015,a016,a017,a018,a019,a020,a021,a022,a023,a024,a025,a026,a027,a028,a029,a030,a031,a032,a033,a034,a035,a036,a037,a038,a039,a040,a041,a042,a043,a044,a045,a046,a047,a048,a049,a050,a051,a052,a053,a054,a055,a056,a057,a058,a059,a060,a061,a062,a063,a064
>perl -e 'local $" = ","; print join ",", <a{@{[q{001}..q{065}]}}>'
a
-Todd
------------------------------
Date: Sat, 24 Nov 2007 14:53:12 +0100
From: Michele Dondi <bik.mido@tiscalinet.it>
Subject: Re: How to get the string Cartesian Products of 2 list
Message-Id: <9magk3p3mh1qijhs7ef980jgsqqhsvkqgj@4ax.com>
On Fri, 23 Nov 2007 06:30:10 -0800 (PST), xueweizhong@gmail.com wrote:
>perl glob in perl5.8 is not power enough than the bash3.0 glob, it
>doesn't support .. operator which is fatal to this issue:
I didn't know that bash 3.* did that. In any case, that's good.
In perl, you can currently use a workaround:
>#!/bin/perl
>
>sub X {split / /,qx/bash -c "echo @_"/}
>
>print "glob:\n";
>print join "\n", glob "{a..b}{1..2}";
local ($",$,)=(",", "\n");
print glob "{@{['a'..'b']}}{@{[1..2]}}"
Of course, someone may implement a bash30_glob() to add to File::Glob.
Michele
--
{$_=pack'B8'x25,unpack'A8'x32,$a^=sub{pop^pop}->(map substr
(($a||=join'',map--$|x$_,(unpack'w',unpack'u','G^<R<Y]*YB='
.'KYU;*EVH[.FHF2W+#"\Z*5TI/ER<Z`S(G.DZZ9OX0Z')=~/./g)x2,$_,
256),7,249);s/[^\w,]/ /g;$ \=/^J/?$/:"\r";print,redo}#JAPH,
------------------------------
Date: Sat, 24 Nov 2007 14:55:52 +0100
From: Michele Dondi <bik.mido@tiscalinet.it>
Subject: Re: How to get the string Cartesian Products of 2 list
Message-Id: <u7bgk3p6nqshhr4ftrv5qt3m64d3l920dn@4ax.com>
On Fri, 23 Nov 2007 07:59:26 -0800 (PST), xueweizhong@gmail.com wrote:
>> {
>> local $" = ','; # List separator
>>
>> my @letters = 'a'..'c';
>> my @numbers = 1..3;
>>
>> my @globbed = glob "{@letters}{@numbers}";
>>
>> print "@globbed\n";
>>
>> }
>I do think these lines are worse than using loop BLOCK. What I want is
>an single expression, not statements with so many nosiy lines.
You can have a single statement, but that's probably even more noisy:
my @globbed = do { local $"=',';
glob "{@{['a'..'c']}}{@{[1..3]}}" };
Michele
--
{$_=pack'B8'x25,unpack'A8'x32,$a^=sub{pop^pop}->(map substr
(($a||=join'',map--$|x$_,(unpack'w',unpack'u','G^<R<Y]*YB='
.'KYU;*EVH[.FHF2W+#"\Z*5TI/ER<Z`S(G.DZZ9OX0Z')=~/./g)x2,$_,
256),7,249);s/[^\w,]/ /g;$ \=/^J/?$/:"\r";print,redo}#JAPH,
------------------------------
Date: Sat, 24 Nov 2007 14:58:53 +0100
From: Michele Dondi <bik.mido@tiscalinet.it>
Subject: Re: How to get the string Cartesian Products of 2 list
Message-Id: <jgbgk354fg3mdf3hlfhbm9fj50j0asivs5@4ax.com>
On Sat, 24 Nov 2007 05:26:24 -0800 (PST), xueweizhong@gmail.com wrote:
>> >> local $" = ','; # List separator
>> >> print glob "{@{['a'..'c']}}{@{[1..3]}}\n";
>
>Is this difference below a language feature or bug?
>
>>perl -e 'local $" = ","; print join ",", <a{@{[q{001}..q{064}]}}>'
>a001,a002,a003,a004,a005,a006,a007,a008,a009,a010,a011,a012,a013,a0
Feature. Try
perl -le 'print for "aa".."bb"'
Michele
--
{$_=pack'B8'x25,unpack'A8'x32,$a^=sub{pop^pop}->(map substr
(($a||=join'',map--$|x$_,(unpack'w',unpack'u','G^<R<Y]*YB='
.'KYU;*EVH[.FHF2W+#"\Z*5TI/ER<Z`S(G.DZZ9OX0Z')=~/./g)x2,$_,
256),7,249);s/[^\w,]/ /g;$ \=/^J/?$/:"\r";print,redo}#JAPH,
------------------------------
Date: Sat, 24 Nov 2007 06:08:41 -0800 (PST)
From: xueweizhong@gmail.com
Subject: Re: How to get the string Cartesian Products of 2 list
Message-Id: <27d0ad61-e392-48a7-b1ef-85b518715814@s12g2000prg.googlegroups.com>
> >>perl -e 'local $" = ","; print join ",", <a{@{[q{001}..q{064}]}}>'
> >a001,a002,a003,a004,a005,a006,a007,a008,a009,a010,a011,a012,a013,a0
>
> Feature. Try
>
> perl -le 'print for "aa".."bb"'
>
You misunderstood me. What i want to understand is the difference
between the output of 2 commands below:
1. perl -e 'local $" = ","; print join ",", <a{@{[q{001}..q{064}]}}>'
2. perl -e 'local $" = ","; print join ",", <a{@{[q{001}..q{065}]}}>'
The 2nd one doesn't out of our expection, can you try this to see
what's going on?:
$perl -e 'local $" = ","; print join ",", <a{@{[q{001}..q{065}]}}>'
a
-Todd
------------------------------
Date: Sat, 24 Nov 2007 14:08:42 +0100
From: "Dr.Ruud" <rvtol+news@isolution.nl>
Subject: Re: searching for a pattern for multiple matches
Message-Id: <fi9bfl.1i0.1@news.isolution.nl>
jhu schreef:
> Can anyone tell me using Perl how to find all matching patterns. So if
> I have this one big string of say a html web page which contains
> multiple IP's and my pattern which is \d{1,3}\.\d{1,3}\.\d{1,3}\.
> \d{1,3} then how do I go about setting up my code in some sort of
> while loop to find all instances of matches ?
#!/usr/bin/perl
use strict;
use warnings;
use Regexp::Common;
local $\ = "\n";
(my $big_string = join "", <DATA>) =~ s/\s*\n\s*/ /g;
print $big_string;
print "-" x 40;
my @ips = $big_string =~ m/$RE{net}{IPv4}/g;
print for @ips;
__DATA__
abc 123.45.6.78 xyz
abc 234.45.68.91 xyz
abc 123.456.78.9 xyz
abc 1.2.3.4 xyz
abc 123.45.678 xyz
abc 234.45.68.910 xyz
abc 1.2.3.4 xyz
See also:
http://search.cpan.org/~abigail/Regexp-Common/lib/Regexp/Common/net.pm
> Also can someone in
> simple terms explain what a back reference is ? Is it simply the
> pattern found ?
A backreference is a sub-pattern. (The word pattern is traditionally
reserved for the whole search pattern.)
With a backreference, you reuse something that is already found by an
earlier capture in the pattern:
m/ ([aeiou]) \1 /x; # two vowels, equal
m/ [aeiou]{2} /x; # two vowels, maybe equal
Now read both perlre and perlretut.
In perlre you'll find:
"Referring back to another part of the match is called a backreference."
In perlretut you'll find:
"Backreferences are simply matching variables that can be used inside a
regexp. This is a really nice feature - what matches
later in a regexp can depend on what matched earlier in the regexp."
--
Affijn, Ruud
"Gewoon is een tijger."
------------------------------
Date: Sat, 24 Nov 2007 04:34:00 -0800 (PST)
From: sisyphus <sisyphus359@gmail.com>
Subject: Re: SvUOK always fails on 64bit platform
Message-Id: <e59ff288-ec7c-474d-add1-0494ddd4fb64@i12g2000prf.googlegroups.com>
On Nov 24, 3:08 pm, Ben Morrow <b...@morrow.me.uk> wrote:
> Quoth Ben Morrow <b...@morrow.me.uk>:
.
.
> Maybe I'll report a bug after 5.10's out.
Good luck with it. Somewhere, within the p5p archives there should be
buried a thread called "-Duse64bitint on Cygwin (Win32)" where I
raised the issue (without receiving any sympathy).
I also made a couple of attempts to raise the issue on perlmonks ( eg
http://www.perlmonks.org/index.pl?node_id=617840 ), where again, it
was not received with any sympathy.
Ben, I lack the expertise and self confidence to pursue the matter
with any conviction, but if you can get somewhere with this, that's
all the better.
Cheers,
Rob
------------------------------
Date: Sat, 24 Nov 2007 14:31:17 +0100
From: "Dr.Ruud" <rvtol+news@isolution.nl>
Subject: Re: SvUOK always fails on 64bit platform
Message-Id: <fi9cka.1eo.1@news.isolution.nl>
Ben Morrow schreef:
> sisyphus:
>> Ben Morrow:
>>> 64bit value SvUOK
>>> 0 .. (1<<63 - 1) false
>>> (1<<63) .. (1<<64 - 1) true
>>
>> There's an interesting little catch here. On many 64-bit builds of
>> perl you'll find that whilst SvUOK returns true for 1<<63, it returns
>> false for 2**63 (because, on perls that don't also have long double
>> support, 2**63 is an NV). If your perl is also built with long double
>> support, then this issue does not arise.
>
> Yes: I noticed 2**63 was a NV, which is why I used << instead :). It
> seems that since ** is pow(3), it counts as a floating-point function.
>
> This all illustrates another point, which is that depending on Perl
> passing a particular representation of data to XS is usually a bad
> idea, *especially* with IV/UV/NV which aren't even distinguishable
> from Perl-space.
>
>> I personally find that behaviour quite annoying ... but I seem to be
>> the only one, and it has been put to me that this would *not* be
>> trivial to fix .... so I reckon the behaviour is here to stay :-)
>
> Well, yeah: given that ** is a floating-point operation, you no longer
> have integer precision in the result:
>
> ~% perl -le'print for (1<<55)-1, sprintf "%.0f", 2**55-1'
> 36028797018963967
> 36028797018963968
>
> though I have to say I don't really understand why this does a
> floating-point subtract, when there's a whole lot of careful code in
> both pp_pow and pp_subtract that tries to do arithmetic in integers
> where possible... Hmmm. The logic in pp_pow goes something like
>
> if (base or power non-integral)
> use pow(3)
>
> if (power negative)
> use pow(3)
>
> if (base is a power of 2) {
> calculate by hand, in NVs
>
> This gives a NV-only result when the result doesn't fit in a
> NV with integer precision.
> }
> else {
> if (
> x**power fits in an UV, where x is the smallest power of 2
> greater than base
> ) {
> calculate by hand, in UVs
>
> This gives a IV/UV result.
> }
> else
> use pow(3)
> }
> }
>
> but I don't really understand why the 'power of 2' branch isn't moved
> inside the second 'else', so small powers of 2 to small powers are
> calculated in UVs where possible.
>
> For that matter, even if you are going to calculate in NVs, the result
> is always going to be accurate (since it's a power of 2) so when the
> result fits in an IV/UV at all the result should be I/UOK. That seems
> like an easy bug to fix, so I must be missing something...
Let's ask p5p.
--
Affijn, Ruud
"Gewoon is een tijger."
------------------------------
Date: Sat, 24 Nov 2007 03:40:24 -0800 (PST)
From: "avilella@gmail.com" <avilella@gmail.com>
Subject: union of 1 and 0 strings
Message-Id: <80ba7bd5-117d-4ec5-b871-b50d1fbd0d39@o6g2000hsd.googlegroups.com>
Hi,
Question:
I have two strings:
DB<32> x $seqchoice
0 '0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 0 0 '
DB<33> x $outgroup
0 '0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 1 0 '
and I want to make the "union" of the "ones" in $outgroup to
$seqchoice, so that I end up with:
DB<32> x $seqchoice
0 '0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 0 '
DB<33> x $outgroup
0 '0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 1 0 '
notice the "1" in the penultimate position in $seqchoice.
Any ideas of a regexp that would do for me?
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
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------------------------------
End of Perl-Users Digest V11 Issue 1059
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