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Posted by Jeff on September 7, 2008, 10:56 pm
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Thanks a million..
I learned something here and it's great
Mark Clements wrote:
> Jeff wrote:
>> Hi all,
>>
>> I have a category / subcategory file that looks like this
>>
>> cereal
>> cereal:cold:cheerios
>> cereal:cold:corn flakes
>> cereal:hot:oatmeal
>> cereal:hot:cream of wheat
>> bread
>> bread:dakine sweet bread
>> bread:wheat
>> bread:white
>>
>> ...... Anyway you get the picture
>>
>> I read the file in and place into array of arrays
>>
>> open FILE, "$file";
>> my @file = (<FILE>);
>> close FILE;
>>
>> my @a;
>> foreach (@file){
>> my @line = split ':', $_;
>> push (@a, \@line);
>> }
>>
>> I want to put this into a hash of hashes where the last element would be
>> equal to 1. something like this
>> $cereal->-> =1;
>> or $bread-> = 1;
>>
>> if later on down the line the file changes so that there is more
>> subcategories, the 1 would be replaced by a new hash like this
>>
>> $cereal->->-> =1;
>> $cereal->-> = 1;
>>
>> I'm having trouble writing a function to do this.
>> Any help or ideas would be appreciated
> The most obvious way of doing it is to use a recursive function (google
> "recursion") to walk the data structure each time a new item is inserted
> (ie for each new line). You probably want something a bit like this
> (insert_item is the recursive function, if that isn't obvious):
>
> mark@hermes:~$ cat cereal.pl
> #!/usr/bin/perl
> #
> use warnings;
> use strict;
>
> use Data::Dumper;
>
> my $root = {};
>
> while(my $line = <DATA> ){
> chomp $line;
> my @items = split /:/,$line;
>
> insert_item( $root, @items );
> }
>
> print Dumper $root;
>
> sub insert_item {
> my $current = shift;
> my $nextkey = shift;
> my @items = @_;
>
> if(@items){
> my $newsubtree;
> if(ref $current->){
> $newsubtree = $current->{ $nextkey };
> }else{
> $newsubtree = {};
> $current->{ $nextkey } = $newsubtree;
> }
> insert_item( $newsubtree, @items );
> }else{
> $current->{ $nextkey } = 1;
> }
> }
>
> __END__
> cereal
> cereal:cold:cheerios
> cereal:cold:corn flakes
> cereal:hot:oatmeal
> cereal:hot:cream of wheat
> bread
> bread:dakine sweet bread
> bread:wheat
> bread:white
> mark@hermes:~$ perl cereal.pl
> $VAR1 = {
> 'bread' => {
> 'white' => 1,
> 'wheat' => 1,
> 'dakine sweet bread' => 1
> },
> 'cereal' => {
> 'cold' => {
> 'cheerios' => 1,
> 'corn flakes' => 1
> },
> 'hot' => {
> 'cream of wheat' => 1,
> 'oatmeal' => 1
> }
> }
> };
>
>
> Mark
>
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