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Hi,

I have a need to sort a hash of hashes! I know it already sounds
complicated, but its the only way I can think of holding the results of the
analysis of some data.

The hash has entries like:

$ips{"F1234"}{"telephone"} = "02088887777"
$ips{"F1234"}{"charge"} = 1000
$ips{"F1234"}{"err_type"} = 0

$ips{"F6638"}{"telephone"} = "02077776666"
$ips{"F6638"}{"charge"} = 500
$ips{"F6638"}{"err_type"} = 2

$ips{"B7877"}{"telephone"} = "02077756666"
$ips{"B7877"}{"charge"} = 445
$ips{"B7877"}{"err_type"} = 2

I need to sort it using the key "err_type"....is this easy? I've never
understood sorting in Perl and so would appreciate any help you can give me.
"err_type" is always a number, if that's relevant!

Thanks in advance,

- raj

Raj wrote:

> $ips{"F1234"}{"telephone"} = "02088887777" $ips{"F1234"}{"charge"} = 1000
> $ips{"F1234"}{"err_type"} = 0
>
> $ips{"F6638"}{"telephone"} = "02077776666" $ips{"F6638"}{"charge"} = 500
> $ips{"F6638"}{"err_type"} = 2
> ...
> I need to sort it using the key "err_type"....is this easy? I've never
> understood sorting in Perl and so would appreciate any help you can give
> me. "err_type" is always a number, if that's relevant!

How about:

sub errtype { $ips{ $a }{err_type} <=> $ips{ $b }{err_type} }

for( sort errtype keys %ips ) {
print "$_\n";
}

This gives the keys of your (level 0) hashes to sort. Sort uses a function
here, gives it $a and $b (the two values that get compared to tell which
is higher). These two vars (two keys of your level 0 hash) we use, well,
as keys for your level 0 hash, but we don't compare (maybe you lookup the
<=> operator) the keys (F6683) but the values of the err_type field in the
hashref saved as value to your level 0 hash.

g,phay

--
http://www.dunkelheit.at/
bellum omnium pater.

Raj wrote:
> I have a need to sort a hash of hashes!

perldoc -q "sort a hash"

> I've never understood sorting in Perl

perldoc -f sort

--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl