Faster way of calulating values in multidimensional array in php?

Question

0 => array(
    'key1' = value
    'key2' = value
    }
1 => array(
    'key1' = value
    'key2' = value
    }

Is there a fast way of getting the sum of id=>key1 and id2=key1 so that I don't have to loop through?

I'd like it to see the array as

array(
    0 = value (key1)
    1 = value (key1)
)

But if it isn't built in somehow, it probably would be another step.

Unless you're dealing with huge arrays I doubt the impact of looping will be too big to manage. Don't worry about performance until you have a performance problem. First and foremost of things your programs should be is correct. — GordonM
– GordonM, Commented Jun 8, 2014 at 22:27
It wouldn't be such a bad feature though, would it? to quickly index multidimensional arrays by a contained key value if asked for. It seems like something people would want to do. Maybe my data model isn't great if it requires loops like this. — justin
– justin, Commented Jun 8, 2014 at 22:31
thanks GordonM. :) well said. The arrays can be very big and some of the bigger ones are taking .08 seconds - and I might need to do 20 or more at a time for a web facing application. I'd like to keep the render time at least under half a second but I don't think anyone will complain if it takes a second. — justin
– justin, Commented Jun 8, 2014 at 22:34
it would require a 'loop' even if it was an internal function, you seem to be seeking magic — user557846
– user557846, Commented Jun 8, 2014 at 22:34
Dagon, that is funny. I thought that some internal functions were handled natively and therefore offer a difference in performance. — justin
– justin, Commented Jun 8, 2014 at 22:37

Mark Baker · Accepted Answer · 2014-06-08 22:52:17Z

1

Using PHP 5.5's array_column() function

$result = array_sum(
    array_column(
        $myArray,
        'key1'
    )
);

for PHP < 5.5

$result = array_sum(
    array_map(
        $myArray,
        function ($value) { return $value['key1']; }
    )
);

answered Jun 8, 2014 at 22:52

Mark Baker

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2 Comments

justin Over a year ago

Thank you! I don't have php 5.5 and had read about array_map, but hadn't figured out how to use it. All of the different options reduce/walk/etc had been a bit confusing.

user557846 Over a year ago

and they still all uses loops :-)

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