php use array as index to array

Question

If I have an array $dictionary and an array $words how can I use an array ($words) to index another array ($dictionary)?

The easiest I can think is:

function dict_dispatch($word,$dictionary) {
    return $dictionary[$word];
}

$translated = array_map('dict_dispatch', $words, 
                          array_fill(0, count($words), $dictionary));

e.g.

For example:

$dictionary = array("john_the_king"=>"John-The-King", "nick_great"=>"Nick-Great-2001");
$words=array("john_the_king","nick_great");

$translated = <??>

assert($translated==array("John-The-King","Nick-Great-2001"));

Notice that $dictionary might be quite large and it would be very nice if this operation is as fast as possible (that's why I don't use foreach in first place)

Are you saying you want to construct an array from another array, using an array of indexes? — Blender
– Blender, Commented Sep 28, 2011 at 15:28
Could you give a small example of what data you would have and what you'd like to end up with? — jprofitt
– jprofitt, Commented Sep 28, 2011 at 15:31
It's correct - but I'm wondering if there's something a bit more native/faster as in Ruby/Python... — neverlastn
– neverlastn, Commented Sep 28, 2011 at 15:46

gen_Eric · Accepted Answer · 2011-09-28 16:01:49Z

2

I don't know how efficient this is, but it works.

$translated = array_values(array_intersect_key($dictionary, array_flip($words)));

edited Sep 28, 2011 at 16:01

answered Sep 28, 2011 at 15:49

gen_Eric

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3 Comments

neverlastn Over a year ago

It's very good but a bit tricky because array_flip is naughty and will not work very well if we have e.g. $words=array("john_the_king","nick_great","john_the_king"); It seems quite efficient as far as I can tell.

Herbert Over a year ago

Actually, a quick test using microtime() shows it to be a bit slower than the OP's code.

gen_Eric Over a year ago

@neverlastn: I didn't think of that, yeah that would be a problem.

Xeoncross · Accepted Answer · 2011-09-28 15:34:21Z

0

Are you talking about something like this where you use array of the keys and another for the values?

$translated = array_combine($words, $dictionary);

answered Sep 28, 2011 at 15:34

Xeoncross

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1 Comment

neverlastn Over a year ago

Thanks a lot! Not exactly. I added an example for clarity.

neverlastn · Accepted Answer · 2011-10-04 18:35:48Z

0

It looks like my original solution is more or less the most efficient.

answered Oct 4, 2011 at 18:35

neverlastn

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