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Re: Usage of hashes with hashes when mulitple values are present

by lune (Pilgrim)
on Nov 22, 2013 at 11:20 UTC ( #1063919=note: print w/replies, xml ) Need Help??


in reply to Usage of hashes with hashes when mulitple values are present

Your code gives me the error
Odd number of elements in hash assignment at ./t4.pl line 6.
Hashes are defined this way:
my %hash = ( somekey => somevalue, ...);
So your code should read:
#!/usr/bin/perl -w use strict; use Data::Dumper; my %w = ( Sub => { 'rbscells' => 'UtranCell=RNC16-4-1', 'UtranCell=RNC16-4-2', 'UtranCell=RNC16-4-3' } ) ; print Dumper(%w);
Now when you look at the output of Data::Dumper, you can see, that what you probably wanted to be an array (the three strings starting with "UtranCell*") are in fact a hash value and another hash key + value:
$VAR1 = 'Sub'; $VAR2 = { 'rbscells' => 'UtranCell=RNC16-4-1', 'UtranCell=RNC16-4-2' => 'UtranCell=RNC16-4-3' };
However, you can't just put an array definition inside a hash - from perldsc:
The most important thing to understand about all data structures in Perl--including multidimensional arrays--is that even though they might appear otherwise, Perl @ARRAYs and %HASHes are all internally one-dimensional. They can hold only scalar values (meaning a string, number, or a reference). They cannot directly contain other arrays or hashes, but instead contain references to other arrays or hashes.
So another change, to define an array reference:
... 'rbscells' => [ 'UtranCell=RNC16-4-1', 'UtranCell=RNC16-4-2', 'UtranCell=RNC16-4-3' , ] ...
You can access the elements of the array as always, via index starting from 0 or with foreach like this:
foreach my $element (@{$w{Sub}->{rbscells}}) { print $element . "\n"; }
To understand nested data structures in perl, please refer to perldsc, especially the chapter about "Hashes of Arrays".

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Re^2: Usage of hashes with hashes when mulitple values are present
by Bhagya (Initiate) on Nov 28, 2013 at 08:59 UTC
    Hi , Please find this piece of code as follows ::
    # Get the list of cells, which has same frequency and SC Id # $t = $w{$_}{frequency} .':'. $w{$_}{sc}; push(@{$w{$t}{cells}}, $_);
    . Here w is a hash variable . for each cell we will be retrieving its corresponding frequency and sc value in following format repectively :
    $w{$_}{frequency} and $w{$_}{sc}
    The above piece of code will collect all the cells which fall in that frequency and sc value .. SO when we give data dumper we will get as follows ::
    '-1:130' => { 'cells' => [ 'SubNetwork=ONRM_ROOT_MO_R,SubNet +work=RNC12,MeContext=RNC12,ManagedElement=1,RncFunction=1,UtranCell=R +NC12-8-2' 'SubNetwork=ONRM_ROOT_MO_R,SubNetwork=RNC12,MeContext=RNC12,ManagedEle +ment=1,RncFunction=1,UtranCell=RNC12-8-8' ] },
    Please let me know how to retrieve the values taht are in array .
      It is hard to follow you, as you omit certain information, that would make it much easiear to answer your question.

      You should just post a runnable piece of complete code, that shwow your problem. Please read ?node_id=510718

      As you just want to know how to *access* the data, why bother about the way you *create* the data structure? Here, I just initialized a hash with the data you provided. Then I can access the elements of the arrayref:

      #!/usr/bin/perl -w use strict; use Data::Dumper; my %w = ( '-1:130' => { 'cells' => [ 'SubNetwork=ONRM_ROOT_MO_R,SubNetwork=RNC12,MeContext=RNC1 +2,ManagedElement=1,RncFunction=1,UtranCell=RNC12-8-2', 'SubNetwork=ONRM_ROOT_MO_R,SubNetwork=RNC12,MeContext=RNC1 +2,ManagedElement=1,RncFunction=1,UtranCell=RNC12-8-8' ], }, ); #print Dumper(\%w); # access one element by index: first = 0 print "Element 0: " . $w{'-1:130'}{'cells'}->[0] . "\n"; print "\n"; # access all available in a foreach loop foreach my $element (@{$w{'-1:130'}{'cells'}}) { print $element . "\n"; }

        Thanks lune and all . It was helpful for me to understand the usage of hash .

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