array_intersect, but for a sub-arrays of a single array variable

Question

I've got an array that looks like this:

$foo = array(
    0 => array('a', 'b', 'c', 'd'),
    1 => array('b', 'c', 'd'),
    2 => array('b', 'd', 'f')
)

I'll refer to $foo[0], $foo[1], and $foo[2] as sub-arrays.

I basically need to perform an array_intersect() across all 3 sub-arrays in $foo. The result should be:

array('b', 'd')

As all three sub-arrays had these values in common. What is the best way to do this?

Some considerations:

There will always be at least one sub-array. No upper limit.
If only one sub-array is provided, it should return that sub-array
If there aren't any common values in all the sub-arrays, an empty array should be returned
If this functionality already exists as a PHP function, I will /facepalm

Check out stackoverflow.com/questions/4704166/…

Ben D
– Ben D

2012-02-24 21:11:30 +00:00
Commented Feb 24, 2012 at 21:11 — Ben D
– Ben D, Commented Feb 24, 2012 at 21:11

Mark Baker · Accepted Answer · 2012-02-24 21:11:34Z

31

+50

$intersect = call_user_func_array('array_intersect',$foo);

Note that keys are preserved from $foo[0]

answered Feb 24, 2012 at 21:11

Mark Baker

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2 Comments

Colin O'Dell Over a year ago

Clever approach, I like it! It works fine if $foo has at least 2 sub-arrays, but fails if there's just one. I fixed this by only calling the above if count($foo) > 1. If count($foo) == 1 I just return the only sub-array. Thanks!

Michael Over a year ago

Thank you @ColinO'Dell $currencies = count($currencies) > 1 ? call_user_func_array('array_intersect', $currencies) : array_shift($currencies); NOTE: I'm typecasting (array) on $currencies so that array_shift returns [].

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