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perl extract "subfields" from text string

Posted on 2013-11-05
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Last Modified: 2013-11-05
Hi,

I have a file with contents as follows:

000000001 ZZZ  $$aTextinA$$bTextinB$$cTextinC
     
There will be several of these, but have just included one for clarity.

For each line, I'm wanting to split the data into variables/fields using a perl script.  Each field is delimited by "$$".  So, for example, from the above I'm wanting to end up with:

$subfield_a = "TextinA"
$subfield_b = "TextinB"
$subfield_c = "TextinC"
           

Equally, if, say, the line was as follows:

000000001 ZZZ  $$aTextinA$$cTextinC
           
I would want to end up with:

$subfield_a = "TextinA"
$subfield_b = ""
$subfield_c = "TextinC"
           
i.e. if a field is not present (in this case $$b)
            
I'm currently doing that as follows (while looping round the file)

@fields = split ('\$\$',$line);
        
	@suba = grep {/^a/} @fields;
        if ( $suba[0] =~ /^a(.*)/ ) {
          $subfield_a = $1;
        } else {
          $subfield_a = "";
        }
        @subb = grep {/^b/} @fields;
        if ( $subb[0] =~ /^b(.*)/ ) {
          $subfield_b = $1;
        } else {
          $subfield_b = "";
        }
	@subc = grep {/^c/} @fields;
        if ( $subc[0] =~ /^c(.*)/ ) {
          $subfield_c = $1;
        } else {
          $subfield_c = "";
        }

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But I'm guessing there is a far more efficient way to be achievening this?
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Question by:yelbow
3 Comments
 
LVL 27

Accepted Solution

by:
wilcoxon earned 2000 total points
ID: 39625525
Try this...
my @tfields = split '\$\$', $line;
shift @tfields; # get rid of "header"
my %fields = (map { m{(\w)(.*)}; $1 => $2 } @tfields);

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The %fields hash now looks like this for your two examples:
a => TextInA
b => TextInB
c => TextInC

and
a => TextInA
c => TextInC

Let me know if you have any questions...
0
 

Author Closing Comment

by:yelbow
ID: 39625731
Perfect, an awful lot cleaner - thanks so much
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LVL 85

Expert Comment

by:ozo
ID: 39626319
my %fields = $line=~/\$\$(\w)([^\$\n]*)/g;

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Or, if you really want the variables in $subfield_a,  $subfield_b, $subfield_c:
  ${"subfield_$1"}=$2 while $line=~/\$\$(.)([^\$\n]*)/g;
but I would not recommend that method.
better might be
 ${${{a=>\$subfield_a,b=>\$subfield_b,c=>\$subfield_c}}{$1}}=$2 while $line=~/\$\$(.)([^\$\n]*)/g;
better still would be to use %fields instead of $subfield_a,  $subfield_b, $subfield_c
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