counting inside the loop

sarvan has asked for the wisdom of the Perl Monks concerning the following question:

Hi,

I have been suggested early on my script. Now the script work in the manner i wanted it. I want a slight modification to that.

se warnings;
use strict;

my $str1 = q/It is a guide to action which ensures that the military a
+lways obey the commands of the party./;
my $str2 = q/It is a guide to action that ensures that the military wi
+ll forever heed Party commands is a guide./;

my $n = 0;
while ( $str1 =~ /(?=(\S+\s+\S+\s+\S+))/g ) {
    my $t1 = $1;
    while ( $str2 =~ /($t1)/g ) {
        print "$1\n";
        $n++;
        }
    }

print "No of matching is : $n\n";
[download]

output:

It is a
is a guide
is a guide
a guide to
guide to action
ensures that the
that the military

No of matching is : 7
[download]

In addition to this i want to count the maximum no.of occurence for each matched combination(three elements).

i.e for eg. if "is a guide" appears two times in $str2. its maximum reference count is 2. likewise i want to compute for all the combinations.

my $count=($str2=~ tr/$t1//);

this counts the no. of times $t1 appeared. But i don't know where to put this inside the loop, so that it can be calculated for all the dynamic values of $t1.

Need help in this.. Thanks..

Comment on counting inside the loop Select or Download Code

Replies are listed 'Best First'.
Re: counting inside the loop by jethro (Monsignor) on Jun 30, 2011 at 13:03 UTC
`$count{$t1}++` [download] This will have the number of occurences of each combination stored in a hash. Think about how it works and you will know where to put it. If not, try out a few locations and observe what happens. Don't forget to print out the hash after all the loops are finished. `my $count=($str2=~ tr/$t1//);` [download] This will count how often the characters in $t1 are in $str2, i.e. if $t1 were "ab" it would count all 'a's and 'b's in $str2. Is that really what you want?	[reply] [d/l] [select]
Re^2: counting inside the loop by AnomalousMonk (Archbishop) on Jun 30, 2011 at 15:09 UTC
`my $count=($str2=~ tr/$t1//);` This will count how often the characters in `$t1` are in `$str2` ... Unfortunately, the `tr///` operator does not interpolate, but the `s///` or, better yet, the `m//` operator can serve here: `>perl -wMstrict -le "my $s = 'foo bar fooo bar foooo bar'; my $cc = 'foz'; ;; my $count = ($s =~ tr/$cc//); print $count; ;; $count = '$c$c$' =~ tr/$cc//; print $count; ;; $count = $s =~ tr/foz//; print $count; ;; $count = $s =~ s{ ([$cc]) }{$1}xmsg; print $count; ;; $count =()= $s =~ m{ [$cc] }xmsg; print $count; ;; $count = $s =~ s{ [$cc] }{}xmsg; print $count; print qq{'$s'}; " 0 5 12 12 12 12 ' bar bar bar'` [download] Note: There is no need for a capture group in the `s///` expression if characters in the string can be counted 'destructively': `$count = $s =~ s{ [$cc] }{}xmsg;` Update: Added `s///` and `m//` examples, discussion.	[reply] [d/l] [select]
Re^2: counting inside the loop by sarvan (Sexton) on Jul 01, 2011 at 11:09 UTC
Hi, For this, `$count=($str=~ tr/($t1)//);` [download] if $t1 has ab. i just want to count how many times ab is their in $str. together. not as seperately 'a' 'b'. What can be done for that..	[reply] [d/l]
Re^3: counting inside the loop by Anonymous Monk on Jul 01, 2011 at 11:27 UTC
AnomalousMonk explains in Re^2: counting inside the loop, use `my $count = () = m/ab/g;`	[reply] [d/l]
Re^4: counting inside the loop by sarvan (Sexton) on Jul 04, 2011 at 05:19 UTC
Re^5: counting inside the loop by Anonymous Monk on Jul 04, 2011 at 06:22 UTC
Re: counting inside the loop by rovf (Priest) on Jun 30, 2011 at 12:53 UTC
The usual way of computing a maximum is to keep a current maximum (for instance initialized to zero), and, whenever you encounter a value which is larger than the current maximum, adjust the current maximum. -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l]


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