And now, for a question that will test your tolerance for those with no perl skill whatsoever. I have been trying to write this script that takes data from a file which has two indices indicating a position in the sky, in degrees. It should sum over one of the indices, adding every data point that corresponds to a particular vertical position, and divide by the number of horizontal steps (360). 
#!/usr/bin/perl -w

use FileHandle;

$fh = new FileHandle "/data/jkerwin/muskyoutput/ravsdec.dat";
die "Can't open RAvsDEC file" unless (defined($fh));
@decavg = ();
$i=0;
$j=0;
@line=();
for ($i=0,$i<147,$i++) {
    $decavg[$i] = 0;
}

while (defined($strip = <$fh>)) {
    ($var1) = (split(/\s+/, $strip))[0];
    ($var2) = (split(/\s+/, $strip))[1];
    ($var3) = (split(/\s+/, $strip))[2];
    $line[0] = $var1;
    $line[1] = $var2;
    $line[2] = $var3;
    $decavg[$line[0]] += $line[2];
}

for ($i=0,$i<147,$i++) {
    $decavg[$i] = $decavg[$i]/360;
    print "$decavg[$i]\n";
}

[download]
Trying to get it to print out what is going into the @decavg array gets me only 9 zeros, which is neither what I want, nor the 147 iterations I expect. Every time I have had the program print up until that point I have gotten some kind of output, but there it fails. This next part is where I have failed time and again. I set up a nested for loop that should assign, for all the vertical degrees, the calculated average value to every horizontal step. 
@decavg2d = ();

for ($i=0,$i<147,$i++) {
    for ($j=0,$j<360,$j++) {
    $decavg2d[$i][$j] = 0;
    }
}

for ($i=0,$i<147,$i++) {
    for ($j=0,$j<360,$j++) {
    $decavg2d[$i][$j] += $decavg[$i];
    print "$decavg2d[$i][$j]\n";
    }
}

[download]
Again, when I try to print this out I get a small number of zeroes. Why won't this print out something meaningful? Do I need to use a hash array instead? (I tried, and it gave me the same kind of error). Thanks in advance for any help you can offer me. - jason "newbie" kerwin

In reply to Stupid loops, or is it just me? by jkerwin

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