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How to store unknown Array into Hash?

gevni
Novice

Dec 19, 2012, 9:50 PM

Post #1 of 12 (2880 views)

How to store unknown Array into Hash?	Can't Post

Hi
i have some arrays, and i don't get how i can store them in hash based on key. I know that i can define hash like that:

my %hash = (
humans => [ 'hamnet', 'shakespeare', 'robyn', ],
faeries => [ 'oberon', 'titania', 'puck', ],
);

But i don't get how i can store unknown array in hash.

Code

 
for($i=0; $i <$data ; $i++){  
some code ...... 
...... 
....... 
for($j=0;$j <= $#$data_2; $j++){ 
............... 
........... 
} 
	push @new_array, $data; 
#I want to store this @new_array into hash based on $i as a key. I don't want to use the reference because for every iteration @new_array contain new array value. I want some thing like that  
    my %join_array[$i] = @new_array; 
} 
output should be 
0->{o,1,2,3} 
1->{2,3,5} 
2-> {5,7,8} 
some thing like that. Thanks

Laurent_R
Enthusiast

Dec 20, 2012, 12:32 AM

Post #2 of 12 (2875 views)

Re: [gevni] How to store unknown Array into Hash? [In reply to]	Can't Post

An array in a hash? The syntax is more like this:

@hash{'foo'} = ['bar', 'baz'];

your remark about not using a reference seems to indicate that you don't really understand what references are about.

BillKSmith
Veteran

Dec 20, 2012, 10:15 AM

Post #3 of 12 (2865 views)

Re: [Laurent_R] How to store unknown Array into Hash? [In reply to]	Can't Post

Laurent is right about your lack of understanding. Please read the FAQ

Code

perldoc -f "How do I declare/create a structure"

Be sure to also read the documents that it refers to (perlref and perldsc). I also suggest reading perllol. If you still cannot understand well enough to answer your original question, post questions about the documents here.
Good Luck,
Bill

rovf
Veteran

Dec 21, 2012, 1:21 AM

Post #4 of 12 (2851 views)

Re: [gevni] How to store unknown Array into Hash? [In reply to]	Can't Post

Code

my %join_array[$i] = @new_array;

It's not entirely clear to me, what you want to achieve (and what is an *unknown* array, as opposed to a *known* one), but this piece of code has several problems:

1. The expression %join_array[$i] doesn't make sense. Do you perhaps mean $join_array{$i} ?

2. You can't localize with 'my' only one element of an array or hash. You can only localize the whole array or hash.

3. In your example (using humans and faeries), you show that a hash element should have as value the *reference* of an array, which is the correct approach. However, @new_array is not a array reference, but an array. To turn an array into a reference to the array, you have to use the \ operator, i.e.

Code

\@new_array

See perldoc perlop

Laurent_R
Enthusiast

Dec 21, 2012, 2:28 PM

Post #5 of 12 (2844 views)

Re: [rovf] How to store unknown Array into Hash? [In reply to]	Can't Post

In Reply To

It's not entirely clear to me, what you want to achieve (and what is an *unknown* array, as opposed to a *known* one)

By "unknown", I think that the OP simply means anonymous arrays. An issue of trying to retranslate into English the translation into some other language of word anonymous.

gevni
Novice

Dec 22, 2012, 12:38 AM

Post #6 of 12 (2839 views)

Re: [Laurent_R] How to store unknown Array into Hash? [In reply to]	Can't Post

Thanks all for your suggestion. Yes I was confused about using reference. Now I get the idea by reading referred perl docs and problem solved by using reference :).

Code

  
for($i=0; $i <$data ; $i++){   
some code ......  
......  
.......  
for($j=0;$j <= $#$data_2; $j++){  
...............  
...........  
}  
 
push @new_array, $data; 
$join_array[$i] = \@data;

Laurent_R
Enthusiast

Dec 22, 2012, 6:26 AM

Post #7 of 12 (2830 views)

Re: [gevni] How to store unknown Array into Hash? [In reply to]	Can't Post

In Reply To

Code

for($j=0;$j <= $#$data_2; $j++){  
}

You probably mean:

Code

for($j=0;$j <= $#data_2; $j++){  
}

because "$#$data_2" is probably not doing you any good.

BTW, there are better ways to loop through the elements of an array than the "C style" loop.

If you really need an explicit interator (the $i variable) for further use:

Code

for my $i (0..$data) { #...

or possibly using the $_ implicit variable:

Code

for (0..$data) { #...

although this later construct with $_ tends to be slightly deprecated nowodays, except in very simple or idiomatic constructs such as:

Code

do_something() foreach (0..10);

And if you don't need an explicit iterator:

Code

foreach my $data2_item (@data_2) { # ...

BillKSmith
Veteran

Dec 22, 2012, 10:14 AM

Post #8 of 12 (2814 views)

Re: [gevni] How to store unknown Array into Hash? [In reply to]	Can't Post

Although this is valid code (assuming that an array @data is defined), It does not answer your original question. I do not think that you will like what it does. The values of all the elements of @join_array will be exactly the same (a reference to the array @data). It does not make any difference if the values in the @data array change between the times that you make these references.

To solve your original problem, your last statement should be:

Code

$join_array[$i] = [@new_array];

The square brackets create a new anonymous array, populate it with the current values from @new_array, and return a reference to the new array. That reference is then stored in $join_array[$i].
Good Luck,
Bill

gevni
Novice

Dec 22, 2012, 10:34 AM

Post #9 of 12 (2809 views)

Re: [BillKSmith] How to store unknown Array into Hash? [In reply to]	Can't Post

What i did to solve my problem I add @new_array = (); at first loop .But your way $join_array[$i] = [@new_array]; is more sensible.

gevni
Novice

Dec 22, 2012, 10:57 AM

Post #10 of 12 (2806 views)

Re: [gevni] How to store unknown Array into Hash? [In reply to]	Can't Post

Now i am trying to store the $join_array[$i] array into @array_index by using $tmp array value as an index.
For example
$join_array[0]= {AA,BB,CC,DD}
and @$tmp{2,1,0,3}# It act as index No.
Then @array_index= {CC,BB,AA,DD}

Code

 
$join_array[$i] = [@new_array]; 
$tmp = $per[$j]->combination($perm->[$j]); 
............ 
.................. 
#I write this code for doing that but I am not sure about [@$tmp[$k]] statement, am i doing right here? 
 
for my $k(0..$tmp) 
{ 
push my @array_index, $join_array->[$j][@$tmp[$k]];  
}

BillKSmith
Veteran

Dec 23, 2012, 12:12 PM

Post #11 of 12 (2751 views)

Re: [gevni] How to store unknown Array into Hash? [In reply to]	Can't Post

No loop is needed, use an array slice.

Code

use strict; 
use warnings; 
my @join_array = ([qw(AA BB CC DD)]); 
my @tmp = (2, 1, 0, 3); 
my @array_index = @{$join_array[0]}[@tmp]; 
print "@array_index\n";

OUTPUT

Code

CC BB AA DD

Edit: Added output
Good Luck,
Bill

(This post was edited by BillKSmith on Dec 24, 2012, 7:25 AM)

gevni
Novice

Dec 24, 2012, 9:13 AM

Post #12 of 12 (2685 views)

Re: [BillKSmith] How to store unknown Array into Hash? [In reply to]	Can't Post

Thanks :)

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