You'll need to iterate it with a nested loop. like so:
$array = array(
array(
"apple",
"colophon",
"byo-fusion-drive",
"scroll-targeting"
),
array(
"apply",
"exploring-web-typography",
"on-performance-content-management"
),
array(
"macbook",
"colophon",
"nifty-minidrive"
)
);
for ($i = 0; $i < count($array); $i++) {
for ($j = $i+1; $j < count($array); $j++) {
var_dump(array_intersect($array[$i], $array[$j]));
}
}
Which outputs:
array (size=0)
empty
array (size=1)
1 => string 'colophon' (length=8)
array (size=0)
empty
A simple modification to the loop gives the expected behavior:
$result = array();
for ($i = 0; $i < count($array); $i++) { //Start from the first array, and continue up to all of them.
for ($j = $i+1; $j < count($array); $j++) { //Start with the current array of $i, +1. So that collisions never occur.
if (count(array_intersect($array[$i], $array[$j])) !== 0) { //If there are common values (the array_intersect() function returns a non-empty array
if (!in_array($array[$i], $result)) $result[] = $array[$i]; //Add the first array (if it's not there already)
if (!in_array($array[$j], $result)) $result[] = $array[$j]; //Add the second array (if it's not there already)
}
}
}
Which outputs
array (size=2)
0 =>
array (size=4)
0 => string 'apple' (length=5)
1 => string 'colophon' (length=8)
2 => string 'byo-fusion-drive' (length=16)
3 => string 'scroll-targeting' (length=16)
1 =>
array (size=3)
0 => string 'macbook' (length=7)
1 => string 'colophon' (length=8)
2 => string 'nifty-minidrive' (length=15)