Hello Discipulus,

grep defined, map {$_->{'k2'}} @aoh;

This works well as long as the hash value is itself defined. But if the hash entry exists with a value of undef:

my @aoh =
(
    { k0 => 'v0'  },
    { k1 => 'v1'  },
    { k2 => undef },
    { k3 => 'v3'  },
);

[download]

then the result of the grep will be indistinguishable from the case in which the hash entry does not exist at all. The following does distinguish between these two cases:

map { exists $_->{k2} ? $_->{k2} : () } @aoh;

[download]

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

In reply to Re^2: extracting elements by key from an array of hashes by Athanasius
in thread extracting elements by key from an array of hashes by ciderpunx

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