array matching problems

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

I have an array of numbers and an array of strings:

@numbers = ('1','1','1','2','2','3','3','4','4','5','6');
@strings = ('hello','you','tree','people','fun','sun','grass','love','
+food','car','rabbit');
[download]

Both arrays have the same number of elements in them. I basically want to concatenate the strings together if the numbers in @numbers are the same. e.g. if $number$i is 1, concatenate all of the correponding elements from @strings together: So would end up with the following new strings:

helloyoutree
peoplefun
sungrass
lovefood
car
rabbit
[download]

My code fails for the last consecutive same number in a row! Can anyone see what i'm doing wrong? Many many thanks !


for (my $i=0; $i< @numbers; $i++)    {
   if (($numbers[$i] == $numbers[$i+1]) || ($numbers[$i] == $numbers[$
+i-1]))     {
                                                                      
+                                                                     
+                                   

              
                push @new_array, "$strings[$i]";
     }
                                                                      
+                                                                     
+                                   
     else {
              push @new_array, ">";
               push @new_array, $strings[$i];
               push @new_array, ">";
              
    }
}
my $j = join ('', @new_array);
$j =~ s/\s+//;
@new_array = split (/>+/, $j);
[download]

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Re: array matching problems by borisz (Canon) on Jul 29, 2004 at 10:08 UTC
`for ( 0 .. $#numbers ) { push @{$h{$numbers[$_]}}, $strings[$_]; } for ( sort { $a <=> $b } keys %h ) { print join('', @{$h{$_}}), "\n"; }` [download] Boris	[reply] [d/l]
Re^2: array matching problems by Anonymous Monk on Jul 29, 2004 at 10:18 UTC
Hi borisz, mant thanks for you response. The code works well but I don't understand it! How can i get it to print each new string to a new array (where each string can be accessed by element number)? AM	[reply]
Re^3: array matching problems by borisz (Canon) on Jul 29, 2004 at 11:00 UTC
the first part build a hash of arrays with the numbers as the key. `%h = ( '1' => [ 'hello', 'you', 'tree' ], '3' => [ 'sun', 'grass' ], '2' => [ 'people', 'fun' ], ... );` [download] The second for loop grap the array and join the words. To grap a entry use `$num = 1; $string = join '', @{$h{$num}}; # string is now helloyoutree $num = 4; # select the string with number 4 ( lovefood ) $string = join '', @{$h{$num}};` [download] Boris	[reply] [d/l] [select]
Re: array matching problems by deibyz (Hermit) on Jul 29, 2004 at 10:47 UTC
Why don't you use a hash to concatenate, with numbers as keys? Something like: `use strict; use warnings; use Data::Dumper; my @numbers = ('1','1','1','2','2','3','3','4','4','5','6'); my @strings = ('hello','you','tree','people','fun', 'sun','grass','love','food','car','rabbit'); my %hash; for (0..$#numbers){ $hash{$numbers[$_]} .= $strings[$_]; } print Dumper(\%hash); __OUTPUT__ $VAR1 = { '6' => 'rabbit', '4' => 'lovefood', '1' => 'helloyoutree', '3' => 'sungrass', '2' => 'peoplefun', '5' => 'car' };` [download] You can also use an array instead of a hash. Regards, deibyz	[reply] [d/l]
Re: array matching problems by davido (Cardinal) on Jul 29, 2004 at 16:08 UTC
There is more than one way to do it... `use strict; use warnings; my @numbers = ('1','1','1','2','2','3','3','4','4','5','6'); my @strings = ('hello','you','tree','people','fun','sun', 'grass','love','food','car','rabbit'); my %cats; # This solution will gobble @strings. foreach ( @numbers ) { $cats{$_} .= shift( @strings ); } print "$cats{$_}\n" foreach sort keys %cats;` [download] Dave	[reply] [d/l]
Re: array matching problems by bgreenlee (Friar) on Jul 29, 2004 at 10:36 UTC
The problem with your code is this: `if (($numbers[$i] == $numbers[$i+1]) ...` [download] When you reach the last element in your list that will be false, because there is no next element. And since the previous element doesn't match, it fails. Without solving it for you (since I'm guessing this is homework), one way to fix it would be to add another 'or' clause that checks to see if it is the last element in the array. Brad	[reply] [d/l]
Re: array matching problems by murugu (Curate) on Jul 30, 2004 at 05:37 UTC
Here is my code, `@numbers = ('1','1','1','2','2','3','3','4','4','5','6'); @strings = ('hello','you','tree','people','fun','sun','grass','love',' +food','car','rabbit'); for (0..$#numbers){ $hash{$numbers[$_]}.=$strings[$_] }; print "$hash{$_}\n" for sort {$a<=>$b} keys (%hash) ;` [download]	[reply] [d/l]