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Printing elements of an array within an array

Posted on 2000-03-09
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Last Modified: 2010-03-05
Here is some sample code that I am stumped with:

#!/usr/bin/perl

my($line1) = "line 1 from a text file";
my($line2) = "line 2 from a text file";
my($line3) = "a NON unique line that needs to be sorted later";
my($line4) = "line 4 from a text file";

my(@array1) = ($line1, $line2, $line4);
my(@array2) = (
                [$line3, @array1],
              );

Basically what I would like to do is:
   sort array based on first dimension
   then print the contents of array1 that is stored within array2

I have read about using a hash table, except that the first element in array2 can be a duplicate, and from what I have read hash table keys have to be unique.

Thanks for you help
Barry
0
Comment
Question by:bmclellan
8 Comments
 
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Expert Comment

by:monas
ID: 2602478
Could you please provide sample input and corresponding output, please...
0
 
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Expert Comment

by:PC_User321
ID: 2602696
It sounds to me as if you don't realise how easy it is to sort in Perl.
Simply use the sort command.  Type the command
   perldoc -f sort
for details (or see http://www.perl.com/pub/doc/manual/html/pod/perlfunc/sort.html)

In your example, if you want the 4 lines sorted, you simply say
   my(@sortedArray) = sort ($line1, $line2, $line3, $line4);

Using a _hash_ to sort eliminates duplicates, so it is not suitable in this application.
0
 
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Expert Comment

by:PC_User321
ID: 2602713
If you want to sort in some way other than alphanumeric ordering based on the entire contents of each element, then you must stipulate your rules in a subroutine, as described in perldoc.

For example:

my(@sortedArray) = sort mySpecialWay ($line1, $line2, $line3, $line4);

sub mySpecialWay {
   .....   # Your code here
}
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Expert Comment

by:PC_User321
ID: 2602780
If you want an answer to the question that is implied by the subject of your post, i.e.  "How do I print elements of @array1 within @array2 in the example below?", the answer is

$i = 1;
foreach (@array1) {
   print "$array2[0][$i++]\n";
}
0
 
LVL 16

Expert Comment

by:maneshr
ID: 2602883
bmclellan ,

please elaborate on your question. instead of giving code snippets. i would suggest that you give this forum the raw input and the desired output.

That way one can clearly visualize your requirements.

Thanks
0
 
LVL 84

Expert Comment

by:ozo
ID: 2603376
Your sample code seems to run without error.  What are you stumped with?
Are you asking this?
perldoc -q "How do I compute the difference of two arrays"
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Accepted Solution

by:
mrachow earned 100 total points
ID: 2603785
Maybe you (bmclellan) want the contained array "moved" when sorting by the non unique lines?!
#!/usr/local/bin/perl -w

my($line1) = "line 1 from a text file";
my($line2) = "line 2 from a text file";
my($line3) = "a NON unique line that needs to be sorted later";
my($line4) = "line 4 from a text file";
my(@array1,@array2,@arrSorted);
my($nIdx);

{
my @arrTmp = ($line1, $line2, $line4);
push @array2, (["Z: ".$line3, \@arrTmp]);
}{
my @arrTmp = ($line2, $line4, $line1);
push @array2, (["A: ".$line3, \@arrTmp]);
}{
my @arrTmp = ($line4, $line2, $line1);
push @array2, (["Y: ".$line3, \@arrTmp]);
}{
my @arrTmp = ($line2, $line2, $line1);
push @array2, (["X: ".$line3, \@arrTmp]);
}{
my @arrTmp = ($line4, $line4, $line4);
push @array2, (["Y: ".$line3, \@arrTmp]);
}

@arrSorted = sort ownSort (@array2);

for($nIdx=0;$nIdx<5;$nIdx++)
{
  print  "$arrSorted[$nIdx][0]","\n";
  print  "@{$arrSorted[$nIdx][1]}","\n";
}

sub ownSort
{
  return ${$a}[0] cmp ${$b}[0];
}
 __END__
 
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Author Comment

by:bmclellan
ID: 2604528
Thanks, that's the answer I was looking for! Once I spend more time with this language and get out of "rookie" status, I will try to articulate my questions better instead of handing you all a riddle to solve on top of the actual question I am trying to ask.


Barry
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