Slice of an array of hashes

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

O Wise Monks; Suppose I had a reference to an array of hashes, such as:

my $aref = [{DB => 'Alpha',
             SOURCE => 'here'},
            {DB => 'Beta',
             SOURCE => 'there'},
            {DB => 'Gamma',
             SOURCE => 'someplace'}];
[download]

How do I extract a list of DB values (Alpha, Beta, Gamma)? Can I do this with a slice?

my @list = @$aref[0..2]->{DB};
[download]

only yields "Gamma". Thanks in advance.

Comment on Slice of an array of hashes Select or Download Code

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Re: Slice of an array of hashes by dragonchild (Archbishop) on Oct 24, 2005 at 19:11 UTC
`my @list = map { $_->{DB} } @$aref;` My criteria for good software: Does it work? Can someone else come in, make a change, and be reasonably certain no bugs were introduced?	[reply] [d/l]
Re: Slice of an array of hashes by Roy Johnson (Monsignor) on Oct 24, 2005 at 19:16 UTC
You can only use arrow notation to extract a single scalar. Slice notation requires that you use the more general `@{block-returning-hashref}{index-list}` form. You should review the two rules for using references. And no, you can't slice along any but the last dimension. dragonchild's map is the solution for what you want to do. Caution: Contents may have been coded under pressure.	[reply] [d/l]
Re^2: Slice of an array of hashes by VSarkiss (Monsignor) on Oct 24, 2005 at 19:29 UTC
And for a quick refresher/reference, try References quick reference. Do not rebuke them with harsh words ... but rather lead them gently - with URLs - so that they may learn wisdom.	[reply]
Re: Slice of an array of hashes by ioannis (Abbot) on Oct 24, 2005 at 20:55 UTC
`my @list = map { $_->{DB} } @$aref;` [download]	[reply] [d/l]
Re: Slice of an array of hashes by murugu (Curate) on Oct 25, 2005 at 08:48 UTC
Here is my try, `my $aref = [{DB => 'Alpha', SOURCE => 'here'}, {DB => 'Beta', SOURCE => 'there'}, {DB => 'Gamma', SOURCE => 'someplace'}]; foreach $arr (@$aref) { push @list,$arr->{DB}; } print $_."\n" for @list;` [download] Regards, Murugesan Kandasamy use perl (;;);	[reply] [d/l]


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