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Hi,

I am a newbie to perl.
I have an array which has few elements like '1,2,3,4,2,3,1,2,1,1,1,4,6,7'
i need to know how many times each element has occurred in the same array.
for example 1-5 times
2-3 times...
could some one throw some light on how i can do this.
thanks in advance..

Regards
Ashwin Thayyullathil Surendran

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>
>
> could some one throw some light on how i can do this.
> thanks in advance..
>

use strict;
use warnings;

my [at] array = (1,2,3,4,2,3,1,2,1,1,1,4,6,7);
my %hash;
foreach my $item ( [at] array){
if (exists $hash{$item}) {
$hash{$item} = $hash{$item} + 1;
} else {
$hash{$item} = 1;
}
}

print " [at] array\n";
while(my ($key,$val) = each %hash) {
print "$key => $val\n";
}

~Parag

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Hello Ashwin,

> I have an array which has few elements like
> '1,2,3,4,2,3,1,2,1,1,1,4,6,7' i need to know how many times each
> element has occurred in the same array. for example 1-5 times 2-3
> times... could some one throw some light on how i can do this.

Store the array contents into a hash, updating the count each time:

=pod code

#!/usr/bin/env perl

use strict;
use warnings;

use Data::Dumper;

my [at] elements = ( 1, 2, 3, 4, 2, 3, 1, 2, 1, 1, 1, 4, 6, 7, );

my %count;
$count{$_}++ for [at] elements;

print Dumper \%count;

=cut

Regards,
Alan Haggai Alavi.
--
The difference makes the difference

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>>>>> "PK" == Parag Kalra <paragkalra [at] gmail.com> writes:

PK> my [at] array = (1,2,3,4,2,3,1,2,1,1,1,4,6,7);
PK> my %hash;
PK> foreach my $item ( [at] array){
PK> if (exists $hash{$item}) {
PK> $hash{$item} = $hash{$item} + 1;
PK> } else {
PK> $hash{$item} = 1;
PK> }
PK> }

this replaces the entire if/else statement:

$hash{$item}++ ;

perl will automatically make undef into 0 without warnings when using
++. there is no need to initialize it the first time. and the rest of
the time it will just increment it. it is a standard perl idiom you need
to know so you don't waste code like that.

uri

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On 2011-03-12 13:17, ashwin ts wrote:
>Hi,

Hello,

>I have an array which has few elements like '1,2,3,4,2,3,1,2,1,1,1,4,6,7'
>i need to know how many times each element has occurred in the same array.
>for example 1-5 times
> 2-3 times...

Use a hash.

#!/usr/bin/perl
use strict;
use warnings;

my [at] array = (1, 1, 2, 4, 2, 1, 9, 42, 0, 0, 0, 1, 0, 0, 2);

my %count;
$count{$_}++ for [at] array;

for my $c( sort{ $b <=> $a } keys(%count) ) {
printf("% 3d appeared %d times\n", $c, $count{$c});
}

Output:

42 appeared 1 times
9 appeared 1 times
4 appeared 1 times
2 appeared 3 times
1 appeared 4 times
0 appeared 5 times


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On Sat, Mar 12, 2011 at 09:20:01AM +0100, magnus [at] trapd00r.se wrote:
> On 2011-03-12 13:17, ashwin ts wrote:
>
> >I have an array which has few elements like '1,2,3,4,2,3,1,2,1,1,1,4,6,7'
> >i need to know how many times each element has occurred in the same array.
> >for example 1-5 times
> > 2-3 times...
>
> Use a hash.

.... says everyone.

If the elements are actually like you say they are, don't use a hash - use
an array.

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Hi,

Thank you all for the support.It helped me a lot.i tried working with arrays
as well as with hash.Both the approaches works fine in the case of a small
array with few elements.
When i tried the same for a large array , i started getting "out of memory"
error.
Any suggestions would be of great help.

Thanks again,

Regards
Ashwin Thayyullathil Surendran



---------- Forwarded message ----------
From: ashwin ts <ashwints17 [at] gmail.com>
Date: Sat, Mar 12, 2011 at 1:17 PM
Subject: help with array elements
To: beginners [at] perl.org


Hi,

I am a newbie to perl.
I have an array which has few elements like '1,2,3,4,2,3,1,2,1,1,1,4,6,7'
i need to know how many times each element has occurred in the same array.
for example 1-5 times
2-3 times...
could some one throw some light on how i can do this.
thanks in advance..

Regards
Ashwin Thayyullathil Surendran

--e0cb4e43cd57247073049e4ae96b--

On 12/03/2011 15:41, ashwin ts wrote:
>
> Thank you all for the support.It helped me a lot.i tried working with arrays
> as well as with hash.Both the approaches works fine in the case of a small
> array with few elements.
> When i tried the same for a large array , i started getting "out of memory"
> error.
>
> Any suggestions would be of great help.

Please show your code. The methods should be fine for all but a
gargantuan array.

Rob

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In article
<AANLkTi=afY09Dh8c2F3tmnCjcM4OM1iHgutAcALn_W5- [at] mail.gmail.com>,
ashwints17 [at] gmail.com (ashwin ts) wrote:

> Hi,
>
> I am a newbie to perl.
> I have an array which has few elements like '1,2,3,4,2,3,1,2,1,1,1,4,6,7'
> i need to know how many times each element has occurred in the same array.
> for example 1-5 times
> 2-3 times...
> could some one throw some light on how i can do this.
> thanks in advance..
>
> Regards
> Ashwin Thayyullathil Surendran


quick write, not tested :

my [at] array = (1,2,3,4,2,3,1,2,1,1,1,4,6,7);
my [at] freq;

for ( [at] array) { $freq[$_]++;}

my $i=0;
for ( [at] freq) {
print "$i : $_ times\n";
$i++;
}


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klp

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On 11-03-12 10:56 AM, kurtz le pirate wrote:
> quick write, not tested

I suggest you test it.


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Shawn

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as it is about coding.

The secret to great software: Fail early & often.

Eliminate software piracy: use only FLOSS.

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At 03:14 -0500 12/03/2011, Uri Guttman wrote:

>this replaces the entire if/else statement:
>
> $hash{$item}++ ;
>
>...it is a standard perl idiom you need
>to know so you don't waste code like that.

Nice!

so

#!/usr/local/bin/perl
use strict;
my %hash;
my [at] array = split //, 12342312111467;
for ( [at] array){
$hash{$_}++
}
for (sort keys %hash){
print "$_ - $hash{$_}x\n"
}


1 - 5x
2 - 3x
3 - 2x
4 - 2x
6 - 1x
7 - 1x

JD

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On Sat, Mar 12, 2011 at 05:31:06PM +0000, Rob Dixon wrote:
> On 12/03/2011 15:41, ashwin ts wrote:
> >
> >Thank you all for the support.It helped me a lot.i tried working with arrays
> >as well as with hash.Both the approaches works fine in the case of a small
> >array with few elements.
> >When i tried the same for a large array , i started getting "out of memory"
> >error.
> >
> >Any suggestions would be of great help.
>
> Please show your code. The methods should be fine for all but a
> gargantuan array.

I suspect you mean that when you store the counts in an array and your
input has large values then you hit "Out of memory!" problems. In that
case an array is not a suitable data structure for your problem and you
should be using a hash.

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On Sat, Mar 12, 2011 at 01:35:31PM -0500, Shawn H Corey wrote:
> On 11-03-12 10:56 AM, kurtz le pirate wrote:
> >quick write, not tested
>
> I suggest you test it.

Is this general advice or do you see a problem with the code? If it is
the former, I agree. If it is the latter, please point out the problem.

Thanks,

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