CODEWITHSUNDEEP
phpmultidimensional-arraycompare
Matt
Matt

Reputation: 1149

PHP Smarter way of comparing a value, to a multidimensional not using foreach?

This is a quick one. Is there a way to compare a given value to a multidimensional array of preset rules, without looping through our rules?

I'll give you an example. Let's say we are evaluating students from 1 to 10. And we want to assign a performance assessment with a few words. So we'd have ranges of marks and what they represent, for example:

$evaluation = array(
    array('from' => 1, 'to' => 3, 'comment' => 'Stop watching TV'),
    array('from' => 4, 'to' => 6, 'comment' => 'Keep trying'),
    array('from' => 7, 'to' => 8, 'comment' => 'Almost there'),
    array('from' => 9, 'to' => 10, 'comment' => 'EMC2')
);

A student got 8, so we'd do:

$grade = 8;
foreach($evaluations as $evaluation) {
    if($grade >= $evaluation['from'] && $grade <= $evaluation['to']) {
        echo $evaluation['comment'];
    }
}

Which I guess is fine. But is there a more neater way to do this? Perhaps a built-in PHP function that would be faster than looping through our set of rules?

Thanks.

Upvotes: 1

Views: 70

Answers (2)

Crisp
Crisp

Reputation: 11447

Think you're over thinking the array a bit, you could key by max value in each range, it's a little less data, and less to evaluate, but in all honesty it seems like a micro optimisation

$evaluation = array(
    3 => 'Stop watching TV',
    6 => 'Keep trying',
    8 => 'Almost there',
    10 => 'EMC2'
);

$grade = 8;
foreach ($evaluation as $limit => $comment) {
    if ($limit < $grade) continue;
    break;
}
echo $comment;

Upvotes: 1

Marc Audet
Marc Audet

Reputation: 46785

A switch statement would be slightly faster but since you are dealing with a 4-element array, almost anything will do.

If you unroll the loop by using a switch statement, you reduce the number of expressions that need to be evaluated since in your loop you need to make a greater than and a less than comparison. Using the switch, you need only one comparison.

There are other PHP functions like array_filter and array_reduce that may lead to the same result if you define the correct callback function, but what you have right now may be as good as anything else.

Upvotes: 2

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