count subset of chars in a line


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count subset of chars in a line

by GrandFather (Saint)

on Jun 22, 2005 at 03:36 UTC ( [id://468897]=CUFP: print w/replies, xml )

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Count all occurrences of characters from a given set in a string.

In the code below $CharSet is the set of characters to count. $SearchStr is the string to count them in.

my $Set = qr/[^$CharSet]/;
length join "", split $Set, $SearchStr;
[download]

Wrapped up in a rather more general sub:

sub CountSetChars
  {
  my $Count;
  my $CharSet = shift;
  my $Set = qr/[^$CharSet]/;
  my $Param;

  while ($Param = shift)
    {
    if (defined @$Param)
      {map {$Count += CountSetChars ($CharSet, $_)} @$Param;}
    elsif (ref $Param)
      {$Count += length join "", split $Set, @$Param;}
    else
      {$Count += length join "", split $Set, $Param;}
    }
  return $Count;
  }
[download]

Comment on count subset of chars in a line Select or Download Code

Replies are listed 'Best First'.
Re: count subset of chars in a line by Zaxo (Archbishop) on Jun 22, 2005 at 03:49 UTC
There's a very pretty way to count them with the tr// operator, `my $vowel_count = tr/AEIOUYaeiouy//;` If you want the character list in a variable, you need to string-eval: `my $foo_count = eval "tr/$foo//";` After Compline, Zaxo	[reply] [d/l] [select]
Re^2: count subset of chars in a line by GrandFather (Saint) on Jun 22, 2005 at 04:01 UTC
Argh, I knew I'd seen a tidy way to do it somewhere. Sorting out the parameter handling for the sub was good exercise though :-). Perl is Huffman encoded by design.	[reply]

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