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

I am a bit stumped.

I have two files. Each file has several columns delimited by single space. There is a leading whitespace. I am only interested in columns 1 and 2. Column 1 is made up of names while column 2 is cholesterol level.

Some names are in both files, so I only want to focus on those names in both.

Knowing this, I have decided that a hash of arrays is an appropriate data structure, so my data is organized as:

Patient 
Cholesterol level

John Kay 
151 128

Sally Gi 
174 145

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There are other patients.

Using the split function, I can designate columns 1 and 2 as various variables, so column 1 = $patient (key) and column two = $level (value) for %health.

I can push $level into an array like so: push (@{($health{$patient}}, $level); However, what if I want to do something with each cholesterol list for each patient? For example, if I wanted to list the levels from lowest to highest, would I use a loop in which I can write:  @levelssorted = sort {$a <=> $b} @{($health{$patient}); and the level numbers for each patient would then be from lowest to highest?

Any help is welcome. Thank you.

Replies are listed 'Best First'.
Re: Push Function and Hash
by tangent (Parson) on Mar 28, 2013 at 01:32 UTC
    Once you have your files read in using  push(@{$health{$patient}},$level); you should end up with a structure like so: 
    %health = (
    'John Kay' => [151,128],
    'Sally Gi' => [174,145],
);

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    You can then iterate through the hash of arrays using while or for: 
    while ( my ($patient,$levels) = each %health ) {
    my @ascending = sort {$a <=> $b} @$levels;
    print "$patient: @ascending\n";
}

for my $patient ( keys %health ) {
    my $levels = $health{$patient};
    my @descending = sort {$b <=> $a} @$levels;
    print "$patient: @descending\n";
}

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    Output: 
    John Kay: 128 151
Sally Gi: 145 174

John Kay: 151 128
Sally Gi: 174 145

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[reply]
[d/l]
[select]
      Appreciate the response.
[reply]

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