find, then store functions into array problem

hideki-san has asked for the wisdom of the Perl Monks concerning the following question:

I have an array called @remaining and a string called $righteq. I want to store any functions that are not + and -signs into the array. Also, the function e^(t plus or minus a number), otherwise known as "e\^$t[\+-](\d+\.?\d*|\.\d+)$" is a special case. I want to detect such a special case, and store it into the array.

$righteq examples:
+++-+++t^n+++f^n+e^(t-123.22)
or
t^n+--++-+f^n++e^(t-123.22)++
or
+++++---+t^n+f^n+++e^(t-123.22)-
[download]

After processing $righteq, the array looks like this:

$remaining[0] is "t^n"
$remaining[1] is "f^n"
$remaining[2] is "e^(t-123.22)"
[download]

edited: Mon May 5 01:41:45 2003 by jeffa - code tags (no br tags)

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Re: find, then store functions into array problem
by pfaut (Priest) on May 04, 2003 at 22:57 UTC

This appears to do what you need.

#!/usr/bin/perl -w
use strict;
while (my $righteq = <DATA>) {
    my @remaining = $righteq =~ /([a-z]\^(?:[a-z]|\([a-z][+-]\d+(?:\.\
+d+)?\)))/g;
    print '$remaining[',$_,'] is ',$remaining[$_],$/ for 0..$#remainin
+g;
}

__DATA__
+++-+++t^n+++f^n+e^(t-123.22)
t^n+--++-+f^n++e^(t-123.22)++
+++++---+t^n+f^n+++e^(t-123.22)-
[download]

Output:

$remaining[0] is t^n
$remaining[1] is f^n
$remaining[2] is e^(t-123.22)
$remaining[0] is t^n
$remaining[1] is f^n
$remaining[2] is e^(t-123.22)
$remaining[0] is t^n
$remaining[1] is f^n
$remaining[2] is e^(t-123.22)
[download]

Update: changed to read into $righteq instead of using $_.

90% of every Perl application is already written. ⇒

dragonchild

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Re: Re: find, then store functions into array problem

by hideki-san (Initiate) on May 04, 2003 at 23:28 UTC

What do I change in your code snippet if the raw data is $righteq, not __DATA__?

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Re: find, then store functions into array problem
by Zaxo (Archbishop) on May 04, 2003 at 22:42 UTC

To extract the strings that are not + or -,

my @remaining = grep {defined} split /[+-]{2,}/, $righteq;
  # fixed 2nd arg error
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I assume you don't mean for these functions to be in perl, since your ^ appears to be exponentiation.

A more detailed regex for your special case can be constructed. Left as an exercise for the reader.

Update: Ok, using your regex:

my @remaining = grep {defined}
                      split /
                            (e\^\(t\+-(\d+\.?\d*|\.\d+)\))
                                   # the special, captured
                            |      # or else
                            [+-]+  # filler, not captured
                            /x,
                            $righteq;
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After Compline,
Zaxo

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