[23545] in Perl-Users-Digest
Perl-Users Digest, Issue: 5753 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Wed Nov 5 09:10:38 2003
Date: Wed, 5 Nov 2003 06:10:12 -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 Wed, 5 Nov 2003 Volume: 10 Number: 5753
Today's topics:
Splitting an array into "even" parts <tore@aursand.no>
Re: Splitting an array into "even" parts <ak+usenet@freeshell.org>
Re: Splitting an array into "even" parts <REMOVEsdnCAPS@comcast.net>
Re: Splitting an array into "even" parts <tore@aursand.no>
Re: Splitting an array into "even" parts (Anno Siegel)
text and html email (Popovici Nicolae)
Re: using a hash as condition selector <fJogham@yahoo.com>
Re: using a hash as condition selector <uri@stemsystems.com>
Re: using a hash as condition selector (Anno Siegel)
Re: Verbose warnings (Anno Siegel)
wolk a byte code tree <pavel@gingerall.cz>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Wed, 05 Nov 2003 12:28:15 +0100
From: Tore Aursand <tore@aursand.no>
Subject: Splitting an array into "even" parts
Message-Id: <pan.2003.11.05.11.27.41.406592@aursand.no>
Hi there!
I need to split an array into "even" parts, so that each resulting array
contains the same number of elements.
Think of it as splitting a list of many names into multiple columns, and
you want x numbers of names in each column so that each column gets filled
up even-wise.
The problem arise, of course, when you have 10 elements and want to split
those into 3 columns. That should be listed like this:
+-------+-------+-------+
| Col 1 | Col 2 | Col 3 |
+-------+-------+-------+
| 1 | 5 | 9 |
| 2 | 6 | 10 |
| 3 | 7 | |
| 4 | 8 | |
+-------+-------+-------+
So far I've come up with this solution:
sub split_array {
my $array = shift; # Array reference
my $parts = shift; # Number of columns to split into
## Make sure $parts is set (default = 2), and that it isn't
## larger than the number of elements in $array
$parts ||= 2;
$parts = @$array if ( $parts > @$array );
## Split
my @split = (); # Will contain the splitted data
my $slice = POSIX::ceil( @$array / $parts ); # Size of each part
for ( 1 .. $parts ) {
if ( $_ == $parts ) {
push( @split, $array );
}
else {
push( @split, splice(@$array, 0, $slice) );
}
}
## Return
return \@split;
}
This code is doubtly the most efficient (I'm always looking for
efficient, yet readable, ways to do things), and I haven't run that many
tests on it either. Any comments on it?
--
Tore Aursand <tore@aursand.no>
------------------------------
Date: Wed, 5 Nov 2003 11:45:45 +0000 (UTC)
From: Andreas Kahari <ak+usenet@freeshell.org>
Subject: Re: Splitting an array into "even" parts
Message-Id: <slrnbqhon4.of8.ak+usenet@mx.freeshell.org>
In article <pan.2003.11.05.11.27.41.406592@aursand.no>, Tore Aursand wrote:
> Hi there!
>
> I need to split an array into "even" parts, so that each resulting array
> contains the same number of elements.
[cut]
> This code is doubtly the most efficient (I'm always looking for
> efficient, yet readable, ways to do things), and I haven't run that many
> tests on it either. Any comments on it?
Here's something that doesn't rely on external modules:
sub split_array
{
my $arr = shift;
my $bins = shift;
my $size = int((scalar @{ $arr })/$bins);
if (scalar @{ $arr } % $bins != 0) {
++$size;
}
my @result;
for my $i (0 .. ($bins - 1)) {
push @result, [ @{ $arr }[$i*$size .. (($i + 1)*$size - 1)] ];
}
return @result;
}
--
Andreas Kähäri
------------------------------
Date: Wed, 05 Nov 2003 06:25:41 -0600
From: "Eric J. Roode" <REMOVEsdnCAPS@comcast.net>
Subject: Re: Splitting an array into "even" parts
Message-Id: <Xns942A4B9315DBFsdn.comcast@216.196.97.136>
-----BEGIN xxx SIGNED MESSAGE-----
Hash: SHA1
Tore Aursand <tore@aursand.no> wrote in
news:pan.2003.11.05.11.27.41.406592@aursand.no:
> Hi there!
>
> I need to split an array into "even" parts, so that each resulting
> array contains the same number of elements.
>
> Think of it as splitting a list of many names into multiple columns,
> and you want x numbers of names in each column so that each column
> gets filled up even-wise.
>
> The problem arise, of course, when you have 10 elements and want to
> split those into 3 columns. That should be listed like this:
>
> +-------+-------+-------+
> | Col 1 | Col 2 | Col 3 |
> +-------+-------+-------+
> | 1 | 5 | 9 |
> | 2 | 6 | 10 |
> | 3 | 7 | |
> | 4 | 8 | |
> +-------+-------+-------+
>
> So far I've come up with this solution:
>
> sub split_array {
> my $array = shift; # Array reference
> my $parts = shift; # Number of columns to split into
>
> ## Make sure $parts is set (default = 2), and that it isn't
> ## larger than the number of elements in $array
> $parts ||= 2;
> $parts = @$array if ( $parts > @$array );
>
> ## Split
> my @split = (); # Will contain the splitted data
> my $slice = POSIX::ceil( @$array / $parts ); # Size of each part
>
> for ( 1 .. $parts ) {
> if ( $_ == $parts ) {
> push( @split, $array );
> }
> else {
> push( @split, splice(@$array, 0, $slice) );
> }
> }
>
> ## Return
> return \@split;
> }
>
> This code is doubtly the most efficient (I'm always looking for
> efficient, yet readable, ways to do things), and I haven't run that
> many tests on it either. Any comments on it?
aplice() pretty much does what you want by itself -- there's no need for
all the special-case-handling code you are surrounding it with.
sub split_array
{
my $array = shift;
my $parts = shift || 2;
my @array = @$array; # working copy
my @split; # result
while (@array)
{
push @split, [splice @array, 0, $parts];
}
return \@split;
}
or even:
push @split, [splice @array, 0, $parts] while @array;
- --
Eric
$_ = reverse sort $ /. r , qw p ekca lre uJ reh
ts p , map $ _. $ " , qw e p h tona e and print
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iQA/AwUBP6jsRmPeouIeTNHoEQJN/gCdG6n983iPY7jp14peWtV09TyG21AAnRH1
pu+8ZH/a6uRkk+sUbRLGbfx0
=fmD3
-----END PGP SIGNATURE-----
------------------------------
Date: Wed, 05 Nov 2003 14:12:28 +0100
From: Tore Aursand <tore@aursand.no>
Subject: Re: Splitting an array into "even" parts
Message-Id: <pan.2003.11.05.13.07.37.613447@aursand.no>
On Wed, 05 Nov 2003 06:25:41 -0600, Eric J. Roode wrote:
> sub split_array
> {
> my $array = shift;
> my $parts = shift || 2;
> my @array = @$array; # working copy
> my @split; # result
>
> while (@array)
> {
> push @split, [splice @array, 0, $parts];
> }
> return \@split;
> }
Fine solution, indeed, but still not satisfying me needs. Let's take a
look at an example:
my @array = ( 1..9 );
my $parts = 4;
Expected result should be:
[
[1,2,3],
[4,5],
[6,7],
[8,9]
]
But your function only returns 3 arrays. A note begins to form in my back
head: Make sure that @array is splittable in $parts parts. :-)
--
Tore Aursand <tore@aursand.no>
------------------------------
Date: 5 Nov 2003 13:52:42 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: Splitting an array into "even" parts
Message-Id: <boavba$b2o$1@mamenchi.zrz.TU-Berlin.DE>
Tore Aursand <tore@aursand.no> wrote in comp.lang.perl.misc:
> On Wed, 05 Nov 2003 06:25:41 -0600, Eric J. Roode wrote:
> > sub split_array
> > {
> > my $array = shift;
> > my $parts = shift || 2;
> > my @array = @$array; # working copy
> > my @split; # result
> >
> > while (@array)
> > {
> > push @split, [splice @array, 0, $parts];
> > }
> > return \@split;
> > }
>
> Fine solution, indeed, but still not satisfying me needs. Let's take a
> look at an example:
>
> my @array = ( 1..9 );
> my $parts = 4;
>
> Expected result should be:
>
> [
> [1,2,3],
> [4,5],
> [6,7],
> [8,9]
> ]
Well, here's a variant that does that. It returns the array of split
parts directly, not a reference to it, but that's trivial to fix.
sub split_array {
my $parts = shift || 2;
my @array = @{ shift()};
my $size = int @array/$parts;
my $rem = @array % $parts;
map [splice @array, 0, $size + ($rem-- > 0)], 1 .. $parts;
}
Anno
------------------------------
Date: 5 Nov 2003 05:50:57 -0800
From: octavp_2000@yahoo.com (Popovici Nicolae)
Subject: text and html email
Message-Id: <e32ba0d5.0311050550.385e9948@posting.google.com>
Hello guys,
Here is my dilema. I am getting my emails using a perl script and
with Mail::Pop3Client module. Now, when I am reading my emails with
BodyToFile , I get the plain/text message and also the plain/html one.
How can I get rid of the plain/html part ?
Any ideeas ?
Thanks.
------------------------------
Date: Wed, 05 Nov 2003 17:51:36 +1100
From: Fred <fJogham@yahoo.com>
Subject: Re: using a hash as condition selector
Message-Id: <3FA89DF8.4090201@yahoo.com>
Gunnar Hjalmarsson wrote:
>
> What made you think that a hash key can be an expression?
Book: Beginning Perl
Chapter 4: Loops and Decisions
Page 128: More Elegant Solutions
http://learn.perl.org/library/beginning_perl/3145_Chap04.pdf
I hope I did not mis-unserstood the authoer. or maybe I could.
thanks
------------------------------
Date: Wed, 05 Nov 2003 06:59:22 GMT
From: Uri Guttman <uri@stemsystems.com>
Subject: Re: using a hash as condition selector
Message-Id: <x74qxjgv1y.fsf@mail.sysarch.com>
>>>>> "F" == Fred <fJogham@yahoo.com> writes:
F> Gunnar Hjalmarsson wrote:
>> What made you think that a hash key can be an expression?
F> Book: Beginning Perl
F> Chapter 4: Loops and Decisions
F> Page 128: More Elegant Solutions
F> http://learn.perl.org/library/beginning_perl/3145_Chap04.pdf
F> I hope I did not mis-unserstood the authoer. or maybe I could.
where in that text did you see anything remotely like what your code was
like? and the book says the code in a hash will be shown a few chapters
later. so please read that chapter and don't just type random characters
at perl and hope it does what you wish.
uri
--
Uri Guttman ------ uri@stemsystems.com -------- http://www.stemsystems.com
--Perl Consulting, Stem Development, Systems Architecture, Design and Coding-
Search or Offer Perl Jobs ---------------------------- http://jobs.perl.org
------------------------------
Date: 5 Nov 2003 09:48:49 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: using a hash as condition selector
Message-Id: <boah21$59$1@mamenchi.zrz.TU-Berlin.DE>
Fred <news@group.com> wrote in comp.lang.perl.misc:
>
> Hello
> I have
> my %hcond =(
> condition => "1",
> condition => "2"
> );
>
> where condition is ($a > $b and $s * $k < $f - 3)
> I have many conditions in this hash.
No, you don't, not in the hash keys. A perl scalar can hold a
"condition" in the form of a coderef, but hash keys are strings,
not general scalars.
> in a code where I need the value out of the hash based on the condition.
> the values of all the variables are known at the time the hash value is
> needed but do I have to
>
> ...code
> ...
> $value = $hcond{$long_condition_written_here}
> ...
> or there is a better way?
You may want to put your conditions in an array (not a hash), where
the array index is the number of the condition to return:
my ( $a, $b, $s, $k, $f);
my @cond;
BEGIN {
@cond = (
sub { 0 }, # always false
sub { $a > $b }, # cond. 1
sub { $s * $k < $f - 3 }, # cond. 2
sub { 1 }, # catch-all
);
}
sub get_cond {
$cond[ $_]->() and return $_ for 0 .. $#cond;
}
Don't forget to assign values to $a...$f before you call get_cond.
Anno
------------------------------
Date: 5 Nov 2003 11:54:29 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: Verbose warnings
Message-Id: <boaodl$6dg$1@mamenchi.zrz.TU-Berlin.DE>
Richard Voss <erutiurf@web.de> wrote in comp.lang.perl.misc:
> Greg Bacon wrote:
> > In article <3fa6ba78$0$1100$3c090ad1@news.plethora.net>,
> > Seebs <seebs@plethora.net> wrote:
> >
> > : Is there any way to find out WHICH variable is uninitialized, short of
> > : breaking a line up into bunches of single lines?
> > : [...]
> >
> > Here's a start:
>
> that will only work with package variables, not with lexicals.
>
> I recommend the debugger.
I have occasionally used something along these lines, which works for
lexicals and package variables, and, in fact, for arbitrary Perl
expressions:
sub report_undef {
my $vars = join ', ', map "'$_'", @_;
my $expr = qq|join( ', ', grep not( defined( eval( \$_))), $vars)|;
qq|print 'undef: ', $expr, "\\n"|;
}
If the code is, for example,
my ( $a, $b, $s, $k, $f);
$b = 123;
$k = 'aaa';
add the line
eval report_undef( qw( $a $b $s $k $f));
to see that $a, $s, and $f are undefined. You still have to type
"eval" literally, and name the variables you want to check. This
is necessary (along with the weirdness of the code in report_undef()),
so that the variables you want to check don't have to be in the
scope where report_undef() is compiled.
Anno
------------------------------
Date: Wed, 05 Nov 2003 13:22:42 +0100
From: Pavel Hlavnicka <pavel@gingerall.cz>
Subject: wolk a byte code tree
Message-Id: <boaq40$29pf$1@ns.felk.cvut.cz>
Hi all,
this is a bit advanced question. I'm developing and application which is
a finite state automaton, where actions to be take on particular state
are described in an external configuration files as a Perl expressions.
To keep the code as safe as possible, I want to allow only particular
function names and variable names might be used in such external
expressions and run a Perl interpreter in a taint mode.
What I need is to pre-check the expression to be evaluated. Regular
expression could become quite complex for this stuff, while walking the
byte code tree seems to be a simple recursive algorithm.
Problem is, that I have no clue where to start and I'm to lazy :) and
under such a time pressure that I need your help. {Please give me some
tips, where to start and how to walk a instruction tree. All I need is
to quit if non-desired tree item is met. I think 'B' module family is
the solution.
Thank you VERY much in advance.
Pavel
--
Pavel Hlavnicka
Ginger Alliance
www.gingerall.com
------------------------------
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)
Message-Id: <null>
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------------------------------
End of Perl-Users Digest V10 Issue 5753
***************************************
