Employing loops and constructing a matrix

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

I have 300+ objects with specific values for x,y,z coordinates, and I want to determine the distance between all 300+ objects and construct a matrix in the following fashion-

             A    B    C
        A   0    10    3

        B   4    0     7

        C   4     1    0
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where the values in the matrix are the distances between A and B, A and C etc. (I just made up the numbers). I've been given data like so,


      s  x         y      z
    A C  79.620  54.720  53.034
    B C  81.822  54.071  50.027
    C C  83.871  51.966  52.424
    ...
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And this equation for distance:

    $d = sqrt(($rx1 - $rx2)**2 + ($ry1 - $ry2)**2 + ($rz1 - $rz2)**2)
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s is a shape parameter that doesn't do anything for this calculation. I realize that I need to work with loops in order to do these crazy number of permutations, but I am not sure how to begin. I tried the following way to get a code to read and store the values in the file, but I could only get it read the first line.

    open(IN, "template.xyz") or die;
    chomp($line = < IN >);
    ($b, @xyz) = split /\s+/, $line; 
    while (chomp($line = < IN >)) {
    ($bb, @xyzvals) = split /\s+/, $line;
    for ($i=0; $i<@xyzvals; $i++) {
    $s{$bb}{$xyz[$i]} = $xyzvals[$i];
        }
    }
    close(IN);
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Any advice on reading/storing the values properly and how to go about doing the permutations?

Original content restored above by GrandFather

I have 300+ objects with specific values for certain coordinates, and I want to determine a value between all 300+ objects and construct a matrix. Any advice on reading/storing the values properly and how to go about doing the permutations? (question resolved)

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Re: Employing loops and constructing a matrix by NetWallah (Canon) on Apr 24, 2012 at 05:07 UTC
Try to get your data into a convenient structure - i'd suggest an array-of-hashrefs. Your results should be a 2-D array. Here is some code to get you started (populated with sample data). You need to figure out how to get your data into this structure: `use strict; use warnings; my @points = ( {X=>79.620, Y=>66, Z=>12.3}, {X=>66.4, Y=>77, Z=>43.1}, {X=>73.6, Y=>55, Z=>93.7} ); my @results; for my $x(0..$#points){ my $p1 = $points[$x]; for my $y (0..$#points){ my $p2 = $points[$y]; my $dist = ( $p1->{X} - $p2->{X} ) 2 + ( $p1->{Y} - $p2->{Y} ) 2 + ( $p1->{Z} - $p2->{Z} ) **2 ; $results[$x][$y] = $dist; } } #------------------- for my $r (@results){ printf "%3.2f\t",$_ for @$r; print "\n"; }` [download] Yes - there is room for optimization, since distances are symmetric, but, at this point, operational and simple code trumps efficient code that introduces complexity. All great truths begin as blasphemies. ― George Bernard Shaw, writer, Nobel laureate (1856-1950)	[reply] [d/l]
Re: Employing loops and constructing a matrix by jwkrahn (Abbot) on Apr 24, 2012 at 05:50 UTC
`chomp($line = < IN >);` [download] `<>` represents two different operators, readline or glob. When you have whitespace it becomes the glob operator so you have: `chomp($line = glob 'IN' );` [download] Or simply: `chomp($line = 'IN' );` [download] `for ($i=0; $i<@xyzvals; $i++) { $s{$bb}{$xyz[$i]} = $xyzvals[$i]; }` [download] In perl that is usually written as: `for my $i ( 0 .. $#xyzvals ) { $s{ $bb }{ $xyz[ $i ] } = $xyzvals[ $i ]; }` [download] Or you could do the same thing with a hash slice: `@{ $s{ $bb } }{ @xyz[ 0 .. $#xyzvals ] } = @xyzvals;` [download]	[reply] [d/l] [select]