just full arrays for array_intersect... how 1

bateman23 · Oct 28, 2004

Hello everybody,

i need to create the intersection of multiple arrays.
I'm aware that this is done with the array_intersect-function.

My problem is, that - at runtime - i don't know which arrays are filled and which are empty. So now the array_intersect throws an error-message "argument x is not an array" - Sure it does, it has to ;-)
My problem is: How do i just put the full arrays into the argument-line of array_intersect and discard the empty ones...?

Any help is greatly appreciated.
Thanx in advance,

Daniel Purucker

sleipnir214 · Oct 28, 2004

The trick is to understand that array intersections are associative operations. You don't have to perform the intersection in a single call of array_intersect().

This code will determine the intersection of a group of variables, checking to make sure that the items to be intersected are non-empty arrays:

Code:

<?php

print '<html><body><pre>';

$a = array(
	array (1, 2, 3, 4, 5),
	array (),
	array (3, 4, 5, 6, 7),
	array (5, 6, 7, 8, 9),
	3
);

$found_array = FALSE;
foreach ($a as $b)
{
	if (is_array($b) && count($b) > 0)
	{
		if ($found_array == FALSE)
		{
			$accumulator = $b;
			$found_array = TRUE;
		}
		else
		{
			$accumulator = array_intersect ($accumulator, $b);
		}
	}
}

print_r ($accumulator);

print '</pre></body></html>';
?>

Perhaps some variation on this theme could be useful to you.

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TANSTAAFL!!

bateman23 · Oct 29, 2004

Thanks a lot. That's awesome...
I really couldn't that figure out by reading the documentation.

---------------------------------------
Visit me @:

http://www.daniel-purucker.de/

sleipnir214 · Nov 1, 2004

No problem.

The documentation doesn't say that you can use array_interset() this way. The only reason I figured it out was from knowing that the intersection of sets is associative.

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just full arrays for array_intersect... how 1

bateman23

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sleipnir214

Programmer

bateman23

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sleipnir214

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