Assignment of Arrays of Hashes

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

Heys all,

Bit of a stupid question, probably, but it's driving me mad .. I have a hash of data which I'm trying to assign to an array using

push @RefHash, \%content;

Now, I've checked that I have clean data up to that point, and that %content is getting populated correctly, and it is.

It seems that the push simply isn't working - anyone have any ideas why this might be the case?

The assignment code etc. is below:

my @selector = ("field1", "field2", "field3", "field4");
open IN, $FILE;

my @RefHash;
while (<IN>) {
  chomp;
  my @inLine = split;

  my %content;
  @content{@selector} = @inLine;

  push @RefHash, \%content;
}
[download]

Like I say, it's probably something stupid, but I can't see it ..

Thanks in advance
--Foxcub

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Re: Assignment of Arrays of Hashes by broquaint (Abbot) on Oct 14, 2002 at 09:48 UTC
~~Look at that `split()` very carefully ...~~ Here's a slightly modified working version of your code `use Data::Dumper; my @selector = ("field1", "field2", "field3", "field4"); my @RefHash; while (<DATA>) { chomp; my @inLine = split /,/; my %content; @content{@selector} = @inLine; push @RefHash, \%content; } print Dumper \@RefHash; __END__ foo,bar,baz,quux one,two,three,four ichi,ni,san,shi` [download] HTH `_________ broquaint` update: uncaught exception `ENOCAFFENE` thrown	[reply] [d/l]
Re: Assignment of Arrays of Hashes by Aristotle (Chancellor) on Oct 14, 2002 at 11:41 UTC
Btw, you may find Converting a CSV list to a list of hashrefs naming the fields interesting. `:-)` Makeshifts last the longest.	[reply]
Re: Assignment of Arrays of Hashes by physgreg (Scribe) on Oct 14, 2002 at 09:55 UTC
I modified the script to use Data::Dumper after the assignment to @content{@selector} and after the loop. Using the test data `test1 test2 test3 test4 test44 afsd wfsdf sdfsd` [download] I got the output `$VAR1 = 'field1'; $VAR2 = 'test1'; $VAR3 = 'field2'; $VAR4 = 'test2'; $VAR5 = 'field3'; $VAR6 = 'test3'; $VAR7 = 'field4'; $VAR8 = 'test4';` [download] after the first assignment, so the hash is indeed being set up correctly. After the loop, my RefHash was set to `$VAR1 = { 'field1' => 'test1', 'field2' => 'test2', 'field3' => 'test3', 'field4' => 'test4' }; $VAR2 = { 'field1' => 'test44', 'field2' => 'afsd', 'field3' => 'wfsdf', 'field4' => 'sdfsd' };` [download] so it appears that the push worked. Perhaps your problem is to do with the way that you are trying to access the array elements? I was able to access it with `print $RefHash[0]{'field2'},"\n";` [download]	[reply] [d/l] [select]
Re: Assignment of Arrays of Hashes by Tanalis (Curate) on Oct 14, 2002 at 09:59 UTC
Nyah, sorted. my in the wrong place wasn't clearing the hash first :/ Oh well, cheers for your help anyway. --Foxcub	[reply]
Re: Assignment of Arrays of Hashes by blm (Hermit) on Oct 14, 2002 at 09:46 UTC
I read your code and think that you mean something like `$content{$selector[1]} = \@inline;` When you use `%hash` you say eg`$hash{'key'} = "Something"`. When you use an array eg `@array` you use eg `$array[1] = "Something"`. In case you don't know putting the following at the top of your scripts turns on useful warnings that help you catch problems quickly. `use strict; use warnings;` [download] Update: OK, OK! I had not seen anywhere that you could do `@hash{'key1', 'key2', 'key3'} = ('value1', 'value2', 'value3');` I am sorry! See Aristotle reply for explanation --blm--	[reply] [d/l] [select]
Re^2: Assignment of Arrays of Hashes by Aristotle (Chancellor) on Oct 14, 2002 at 11:38 UTC
No, he is using the hash correctly. You can assign to multiple hash keys at once by saying `@hash{'key1', 'key2', 'key3'} = ('value1', 'value2', 'value3');`. This is known as a "slice", and that's what he's doing. Makeshifts last the longest.	[reply]