I would like to know how get the sum of all values in a specific "row" of an array.
I got this array for example:
[0] {array( "date" => "2015-01-01", "value" => 5) }
[1] {array( "date" => "2015-01-02", "value" => -3) }
...
Now I would like to get the sum of all "values" in this array - in this case it would be 2.
How can I do this in PHP?
I'd say array_column
fits that description rather nicely, don't you?
$values = array_column($array, 'value');
var_dump($values);
And the aptly named array_sum
will finish it all off nicely
$sum = array_sum($values);
In case you're still on PHP5.4 ( array_column
wasn't introduced until 5.5):
$sum = 0;
foreach ($array as $sub)
{
$sum += $sub['value'];
}
will do just fine. It'll probably outperform the array_column
+ array_sum
approach anyway (because it's not calling functions, but relying on language constructs)
There is a specific function for this: array_reduce
<?php
$array = array(array('date'=>'', value=>5),array('date'=>'', value=>-3));
$t = array_reduce($array, function($result, $item){
$result['value'] = $result['value'] + $item['value'];
return $result;
}, array('value'=>0));
array reduce gets an array, a function to use on that array, and the third paramter is the initial array you use on the first call of the function.
I used an array here so you can, if you want, also do something with the date (max or min). You could ofcourse just use an int. Then it looks simpeler:
$t = array_reduce($array, function($result, $item){
$result = $result + $item['value'];
return $result;
}, 0);
You can achieve this with a combination of array_sum()
and array_map()
like so:
$sum = array_sum(
array_column(
$originalArray,
'value'
)
);
If you're on an older version of PHP (< 5.5.0), then you could use the following:
$sum = array_sum(
array_map(
function($arr) {
return $arr['value'];
},
$originalArray
)
);
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