array_sum()

(PHP 4 >= 4.0.4, PHP 5, PHP 7)

对数组中所有值求和

说明

array_sum(array $array):number

array_sum()将数组中的所有值相加，并返回结果。

参数

$array

输入的数组。

返回值

所有值的和以整数或浮点数的结果返回，$array为空时则返回0。

范例

Example #1array_sum()例子

<?php
$a = array(2, 4, 6, 8);
echo "sum(a) = " . array_sum($a) . "\n";
$b = array("a" => 1.2, "b" => 2.3, "c" => 3.4);
echo "sum(b) = " . array_sum($b) . "\n";
?>

以上例程会输出：

sum(a) = 20
sum(b) = 6.9

If you want to find the AVERAGE of the values in your array, use the sum and count functions together. For example, let's say your array is $foo and you want the average...
<?php
$average_of_foo = array_sum($foo) / count($foo);
?>

If you want to check if there are for example only strings in an array, you can use a combination of array_sum and array_map like this:
<?php
function only_strings_in_array($arr) {
  return array_sum(array_map('is_string', $arr)) == count($arr);
}
$arr1 = array('one', 'two', 'three');
$arr2 = array('foo', 'bar', array());
$arr3 = array('foo', array(), 'bar');
$arr4 = array(array(), 'foo', 'bar');
var_dump(
  only_strings_in_array($arr1),
  only_strings_in_array($arr2),
  only_strings_in_array($arr3),
  only_strings_in_array($arr4)
);
?>
This will give you the following result:
bool(true)
bool(false)
bool(false)
bool(false)

For clarity, array indices containing boolean values such as TRUE and FALSE are added up as though they are 1 and 0 respectively.

If some array elements arent integers, function will change them to integers (content of array will not change) type and then sum them.
Example:
<?php
$foo[] = "12";
$foo[] = 10;
$foo[] = "bar";
$foo[] = "summer";
echo array_sum ($foo); //same as echo "22";
?>

Microsoft Excel - SUMIF()
function sumif($array,$criteria,$sum_array){ 
 if(is_array($array) && is_array($sum_array) && trim($criteria)!= ""){ 
  $array_count = (count($array) < count($sum_array)) ? count($array): count($sum_array);
  for($i=0;$i<$array_count;$i++){
   if(ereg("^<",$criteria)){
    $value = ereg_replace("^<","",$criteria);
    $result += $array[$i] < $value ? $sum_array[$i]:0; 
   }
   elseif(ereg("^>",$criteria)){ 
    $value = ereg_replace("^>","",$criteria);
    $result += $array[$i] > $value ? $sum_array[$i]:0;
   }
   else{
    $value = $criteria;
    $result += $array[$i] == $value ? $sum_array[$i]:0;
   }
   
  }
  return $result ? $result:0;
 }
}

I'm not sure if something similar already exists, but I needed it so I made it:
<?php
 /* Performs a pitagoric sum of the elements in $arr
  The pitagoric sum of a set of values is the square root of
  the sum of the sqare power of each value. So, for a, b, c
  it's sqrt(a^2 + b^2 + c^2) */
 /* If any element of $arr is an array itself, the array_sum
  will be used. Alternatively, the values could be used by
  recursion. Returns the integer part (floor) */
 function array_pitag_sum($arr) {
  if(is_array($arr) {
   $ret = 0;
   foreach($arr as $i) {
    if(is_array($i)) {
     $s = array_sum($i);
     $ret += $s*$s;
    } else {
     $ret += $i*$i;
    }
   }
   return floor(sqrt($ret));
  } else {
   return $arr;
  }
 }
?>

Here is how you can multiply two arrays in the form of matrixes using a bit of matrix algebra (M*M).
By calling the function multiplyMatrix, you will be multiplying two sparse matrixes (zeros need not be included in the array for the operation to be performed).
<?php
$M = array(
0=>array(1=>1,4=>1),
1=>array(2=>1,3=>1),
3=>array(1=>1),
4=>array(5=>1),
5=>array(6=>1)
);
$M1 = multiplyMatrix($M, $M); //multiplying $M by itself
echo '<pre>';print_r($M1);echo '</pre>';
function multiplyMatrix($M1, $M2)
  {
#Helena F Deus, Oct 06, 2008
##Multiply two matrixes; $M1 and $M2 can be sparse matrixes, the indexes on both should match
    if(is_file($M1)) {$matrix1 = unserialize(file_get_contents($M1));}
    else $matrix1 = $M1;
    
      
    #transpose M2
    $M2t = transpose($M2);
    
    foreach ($M2t as $row=>$tmp) {
      ##sum the result of the value in the col multiplied by the value in the vector on the corresponding row
        
        foreach ($M1 as $row1=>$tmp1) {
          
          $multiply[$row1] = array_rproduct($tmp,$tmp1);
          
          if(!$multiply[$row1]){
             exit;
            }
        }
        
        foreach ($multiply as $row1=>$vals) {
          
          $sum[$row][$row1]=array_sum($vals);
        }
        
    }
  
  $r=transpose($sum);
  
  return ($r);
  }
function transpose($M)
{
foreach ($M as $row=>$cols) {
      
      foreach ($cols as $col=>$value) {
         if($value)
         $Mt[$col][$row]=$value;
      }
    }
    ksort($Mt);
    
return ($Mt);      
}
function array_rproduct($a1, $a2)
{
  
  
  foreach ($a1 as $line=>$cols) {
    $a3[$line] = $a1[$line]*$a2[$line];
    foreach ($a2 as $line2=>$cols2) {
      $a3[$line2] = $a1[$line2]*$a2[$line2];
    }
  }  
  ksort($a3);
  
  
  return ($a3);
  
  
}
?>

Nice and clean if you know what I mean:
function makeRecursive($ar = "")
{
  $toflat = array( $ar );
  $res = array();
  while (($r = array_shift($toflat)) !== NULL)
    foreach ($r as $v)
      if (is_array($v))
        $toflat[] = $v;
      else
        $res[] = $v;
  return $res;
}
$data = [0,0,0,[0,0,[0,1,0,],0],0];
echo array_sum(makeRecursive($data));

array_sum can be used to caculate the cross sum in a very short way:
array_sum(str_split('17243'))
php frameworks like rexo do it like this; it's faster then do it by iteration.