http://www.perlmonks.org?node_id=38743

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question: ⭐ (hashes)

How do I dynamically create a hash table?

Originally posted as a Categorized Question.

  • Comment on How do I dynamically create a hash table?

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Re: How do I dynamically create a hash table?⭐
by tedv (Pilgrim) on Oct 27, 2000 at 20:54 UTC 
      use strict;

  my %hash = ();
  foreach $value (@some_list) {
    my $key = make_some_key($value);
    $hash{$key} = $value;
  }

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    In other words, just assign a new key/value pair using $hash{$key} = $value. It's the logical compliment of how you'd access a hash value: $value = $hash{$key}

    -Ted
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Re: How do I dynamically create a hash table?
by Anonymous Monk on Oct 19, 2004 at 18:42 UTC
    In only 1 line! 
    %new_hash = (split(/;/,$variable_with_keys_and_values));

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    For example: 
    %new_hash = (split(/;/,'apple;good;banana;good;citrus;good;no doughnut
+;bad cop'));

print $new_hash{'no doughnut'};

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    Outputs the value associated with the key 'no doughnut'
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      This would probably be more clear if you said print $new_hash{'doughnut'}; instead of print $new_hash{'no doughnut'}; There is no item with key 'no doughnut'.
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        Thanks; Anonymous Monk had originally had everything say "doughnut". one of the QandAEditors changed it to "no doughnut" and apparently flubbed it. Now fixed.
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Re: How do I dynamically create a hash table?
by kharris (Initiate) on Sep 25, 2002 at 18:51 UTC
    I just got done with this sort of thing. It looks like this.

    my ($url, @rest, $url_rec, @url_keys);
($url, @rest)=split /\|/,$_;
if($#rest == 3) # We're re-building. 
{
  @url_keys= qw{url_last_checked_return_code url_cat_id url_descriptio
+n url_last_checked};
}        
if($#rest == 1) # We're adding.
{
  @url_keys = qw{url_cat_id url_description};
}
foreach my $key (@url_keys) {
  $url_rec->{$key} = pop @rest;
}

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    I know that someone above adept-level could have done this more elegantly efficiently, but it works...so far. ;-)

    kevin

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Re: How do I dynamically create a hash table?
by Anonymous Monk on Oct 08, 2001 at 19:14 UTC
    We have tried out this way:

    @list_of_elements = split /;/,$variable_with_keys_and_values);
%new_hash = (@list_of_elements);

    We think this is more simple (just two lines!)

    - Franco e Giuseppe.
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Re: How do I dynamically create a hash table? (A straightforward Q, I know!)
by merlyn (Sage) on Oct 27, 2000 at 03:25 UTC
    This question needs more context. Do you mean: 
    %hash_table = @dynamically_read_data;

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    Or if not, then what?

    Originally posted as a Categorized Answer.

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Re: How do I dynamically create a hash table? (A straightforward Q, I know!)
by davorg (Chancellor) on Oct 27, 2000 at 12:06 UTC

    As merlyn says, it's not very clear what you're asking. You might find that the examples in the perldsc manual page help you tho'.

    Originally posted as a Categorized Answer.

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Re: How do I dynamically create a hash table? (A straightforward Q, I know!)
by kharris (Initiate) on Sep 25, 2002 at 18:51 UTC
    I just got done with this sort of thing. It looks like this.

    my ($url, @rest, $url_rec, @url_keys);
($url, @rest)=split /\|/,$_;
if($#rest == 3) # We're re-building. 
{
  @url_keys= qw{url_last_checked_return_code url_cat_id url_descriptio
+n url_last_checked};
}        
if($#rest == 1) # We're adding.
{
  @url_keys = qw{url_cat_id url_description};
}
foreach my $key (@url_keys) {
  $url_rec->{$key} = pop @rest;
}

    [download]

    I know that someone above adept-level could have done this more elegantly efficiently, but it works...so far. ;-)

    kevin

    Originally posted as a Categorized Answer.

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