Hi perlmonks,

I am trying to bin the 2D data shown below in a grid. i.e. (x1,y1), (x1,y2),...(x1,yn), (x2,y1), (x2,y2),...(x2,yn), etc.
FYI this is not a school assignment, etc.

X Y
3.70722 0.54617
3.67342 0.64892
3.75017 0.85075
3.82831 0.83506
3.71852 0.79251
3.80706 0.70426
3.91839 0.94094
3.90726 0.81722
3.89007 0.76107
3.98006 0.62477

Here's how I am proceeding:
1). Create an array of x-values (@egvx)
2). Create an array of y-values (@egvy)
3). Get the minimum and maximum values of each array ($minx, $maxx, $miny, $maxy)
4). Create two ranges: @rgx = ($minx..$maxx) and @rgy = ($miny..$maxy) with regular spacings of 0.1.
5). For each value in @egvx, loop through all the values in @egvy and check where each pair of values lies by looping through bins defined by ($rgx[$x] and $rgx[$x] + 0.1), and ($rgy[$y] and $rgy[$y] + 0.1)
6). If a pair of @egvx and @egvy values falls between ($rgx[$x] and $rgx[$x] + 0.1), and ($rgy[$y] and $rgy[$y] + 0.1) increase the count of that bin.

Steps five and six are the problem areas. First, I have 196 bins, but after running the script, I get only 90 bins. Secondly, the bin counts are all zero.

It's a pretty long code. I have shown only that section where I try to handle steps 5 & 6.

my $j1x = 0; my $j1y = 0; my $k = 0; 
my $ctxy = 0;

#create the number of bins
while($j1x < $kx)
{
        while($j1y < $ky)
        {
                $bin[$ctxy] = "bin\t$num"; 
                $binCnt[$ctxy] = 0;
                $num++;
                $ctxy++;
                $j1y++;
        }
        $j1y = 0;
        $j1x++;
}


#@egvx = x-values, @rgx = range of x-values, @binx = x-bins
#@egvy = y-values, @rgy = range of y-values, @biny = y-bins
#@upy and @upx = upper-boundaries of yth and xth bins

my $j = 0; my $x = 0; my $y = 0; my $c = 0;

open(TST,">test.txt");
while($j < $i) #loops through the x-values
{
  while($c < $i)#loops through the y-values
  {
    while($y < $ky)#loops through the y-bins
    {
      $upy[$y] = $rgy[$y] + 0.1;

      while($x < $kx)#loops through the x-bins
      {
        $upx[$x] = $rgx[$x] + 0.1;

        #check which bin the x-value falls into
        if(($egvx[$j] > $rgx[$x])and($egvx[$j] < $upx[$x]))
        {
          #print TST "$egvx[$j]\t$rgx[$x]\t$upx[$x]\n";
          #record x-center of the bin
          $binx[$x] = ($rgx[$x] + $upx[$x])/2;

          #check which bin the y-value falls into
          if(($egvy[$c] > $rgy[$y])and($egvy[$c] < $upy[$y]))
          {
            #record y-center of the bin
            $biny[$y] = ($rgy[$y] + $upy[$y])/2;
            $binCnt[$x] += $binCnt[0];
            print TST "$binCnt[$x]\n";
            #print TST "x: $egvx[$j] $rgx[$x] $upx[$x]\t y: $egvy[$j]\
+t$rgy[$y]\t$upy[$y]\n";
          }
        }
        $x++;
      }
     $x = 0; #reset x-bins
     $y++;
   }
   $y = 0; #reset y-bins
   $c++;
  }
  $c = 0; #reset y-values until all x-values have been tested
  $j++;
}

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In reply to 2D binning by austinby

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