Re: My 'perldar' tells me there is a 'better' solution for this list operation

Or how about a solution using a regular expression.

my @l1 = qw(Date IndexID Maturity OnTheRun CompositePrice 
CompositeSpread ModelPrice ModelSpread Depth Heat);

my @l2 = qw(OnTheRun CompositePrice CompositeSpread Depth);

my @l3;

{
    local $" = q{|};
    @l3 = map {m{^@l2$} ? $_ : q{null}} @l1;
}
[download]

Cheers,

JohnGG

Comment on Re: My 'perldar' tells me there is a 'better' solution for this list operation Download Code

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Re^2: My 'perldar' tells me there is a 'better' solution for this list operation by an0 (Initiate) on Nov 04, 2006 at 16:21 UTC
To johngg: it seems your code does not work at all; even if rectified to work, it is not so efficient when regex engine is involved. My suggestion is: sort (lexicographically) the lists first, then the search can be done in one whole pass through the two lists.	[reply]
Re^3: My 'perldar' tells me there is a 'better' solution for this list operation by johngg (Canon) on Nov 04, 2006 at 18:02 UTC
It works fine for me. In what way did it not work for you? I did not show the `use strict;` and `use warnings;` I always put at the top of my scripts in my first post. Here's the whole script again, it's output and some info on my platform and perl version $ cat spw582186 #!/usr/bin/perl # use strict; use warnings; my @l1 = qw(Date IndexID Maturity OnTheRun CompositePrice CompositeSpread ModelPrice ModelSpread Depth Heat); my @l2 = qw(OnTheRun CompositePrice CompositeSpread Depth); my @l3; { local $" = q{\|}; @l3 = map {m{^@l2$} ? $_ : q{null}} @l1; } print qq{$_\n} for @l3; $ ./spw582186 null null null OnTheRun CompositePrice CompositeSpread null null Depth null $ uname -a SunOS b4rsk 5.10 Generic_118833-03 sun4u sparc SUNW,Ultra-60 $ perl -v This is perl, v5.8.4 built for sun4-solaris-64int (with 28 registered patches, see perl -V for more detail) Copyright 1987-2004, Larry Wall Perl may be copied only under the terms of either the Artistic License + or the GNU General Public License, which may be found in the Perl 5 source ki +t. Complete documentation for Perl, including FAQ lists, should be found +on this system using `man perl' or `perldoc perl'. If you have access to + the Internet, point your browser at http://www.perl.com/, the Perl Home Pa +ge. $ [download] You may well be right regarding efficiency, I haven't run any benchmarks. The object of the post was to show an alternative method to those already given. Cheers, JohnGG	[reply] [d/l] [select]
Re^4: My 'perldar' tells me there is a 'better' solution for this list operation by OfficeLinebacker (Chaplain) on Nov 04, 2006 at 18:22 UTC
Hi, John. Looks like you posted this as I was composing my reply below. I get it now. You're doing it exactly how I was thinking of the problem at first, making the regular expression be the array and the LHV of the match be the individual element. That's a clever use of $" to make the separator be the alternation operator for regexps ('\|'). I thought \| only worked in parentheses, though. I stand corrected. _________________________________________________________________________________ I like computer programming because it's like Legos for the mind.	[reply]


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