array comparison

[babygodzilla]

if i have multi-dim arrays like so: $a[$x][$y]

$a[0][0]
$a[0][1]
$a[0][2]

$a[1][0]
$a[1][1]

$a[2][0]
$a[2][1]
$a[2][2]
$a[2][3]

how would i compare all elements of $a[0], [1], and [2] with each other? so i want to compare

$a[0][0] - $a[1][0]
$a[0][0] - $a[2][0]
$a[1][0] - $a[2][0]

see what i mean? i want to take one element out of each group and compare them to each other. but i do not want to compare elements $y in the same group $x, like $a[0][0] shouldnt be compared with $a[0][1]. im confused with the loop

[jubripley]

could you do something like this?

for ($i1=0; $i1<$num_rows; ++$i1) {
  for ($j1=0; $j1 < $num_cols; ++$j1) {
    for ($i2=0; $i2<$num_rows; ++$i2) {
      for ($j2=0; $j2<$num_cols; ++$j2) {
        if ($i1 != $i2) {
           compare ($a[$i1][$j1], $a[$i2][$j2]);
         }
      }
    }
  }
}

where $num_rows and $num_cols are from the size of your array and compare() is whatever you're doing to compare the 2 values.

[babygodzilla]

no i dont think thatll work because thatll do the comparison in this order

$a[0][0] - $a[1][0]
$a[0][0] - $a[1][1]
$a[0][0] - $a[1][2]

i need it to go like

$a[0][0] - $a[1][0]
$a[0][0] - $a[2][0]
$a[1][0] - $a[2][0]

$a[0][0] - $a[1][0]
$a[0][0] - $a[2][1]
$a[1][0] - $a[2][1]

$a[0][0] - $a[1][0]
$a[0][0] - $a[2][2]
$a[1][0] - $a[2][2]

$a[0][0] - $a[1][1]
$a[0][0] - $a[2][0]
$a[1][1] - $a[2][0]

$a[0][0] - $a[1][1]
$a[0][0] - $a[2][1]
$a[1][1] - $a[2][1]

this is so frickin confusing....