合并2个数组并合并数字键的结果

Question

I have 2 arrays in which I wish to merge/group together by each numerical key. eg

Array1
(
    [2009] => 131
    [2008] => 940
    [2007] => 176
    [2006] => 1
)
Array2
(
    [2008] => 9
    [2007] => 3
)

I would like the output to be:

Array (
    [2009] => 131
    [2008] => Array (
                     [0]=>940
                     [1]=>9
                    )
    [2007] => Array (
                     [0]=>176
                     [1]=>3
                    )
    [2006] => 1
)

How on earth do I achieve this? I have tried array_merge but I lose my keys and they don't get grouped.

Answer 1

If I see that right you only want those key to hold an array, that reference more than a single value. The other keys should still refer to scalar values...

So you need a two step strategy:

// 1.) turn _all keys into arrays
foreach (array($input1,$input2) as $array)
    foreach ($array1 as $key=>$val)
        $output[$key][]=$val;
// 2.) reconvert elements with single entry to a scalar value again
foreach ($output as $key=>$candidate)
    if (1==count($candidate))
        $output[$key]=$candidate[0];
// test output
print_r($output);

Answer 2

Why don't you just write a method to merge them?

/**
Merge original_array with new_array
@param array original_array
@param array new_array
*/
function merge_array($original_array, $new_array)
{
    $merged_array = array();
    if(is_array($original_array) && is_array($new_array))
    {
        foreach($original_array as $key => $value)
        {
            $merged_row[] = $value;
            if(isset($new_array[$key]))
            {
                $merged_row[] = $new_array[$key];
            }
            $merged_array[$key] = $merged_row;
        }
    } else $merged_array = $original_array;
    return $merged_array;
}

Answer 3

Just unit tested this. It should union the arrays. Mind you it could be improved in terms of performance. Items without an associative key will be grouped into key '0'.

   public function merge(&$ar, $ar2) {
      foreach ($ar as $k => $v) {
         if (isset($ar2[$k])) {
            $ar[$k] = array_merge(array($ar[$k]), array($ar2[$k]));
         }
      }

      foreach ($ar2 as $k => $v) {
         if (!isset($ar[$k])) {
            $ar[$k] = $ar2[$k];
         }
      }    
    }

The unit test:

public static function test_merge() {
      $ar1 = array(45, 'a' => 44, 'dog' => array(1), 'cat' => 3);
      s($ar1, array(2, 'dog' => 2, 'cat' => 4, 'stuff' => 4.3));
      print_r($ar1);
}

The result:

IArray
(
    [0] => Array
        (
            [0] => 45
            [1] => 2
        )

    [a] => 44
    [dog] => Array
        (
            [0] => Array
                (
                    [0] => 1
                )

            [1] => 2
        )

    [cat] => Array
        (
            [0] => 3
            [1] => 4
        )

    [stuff] => 4.3
)

Answer 4

<?php
$arrOne = array( 2009 => 131,  2008 => 940,  2007 => 176,  2006 => 1);
$arrTwo = array( 2008 => 9, 2007=> 3, 2011 => 67);
$output = array();


foreach($arrOne as $key=>$value){
  if(isset($arrTwo[$key])){
    $output[$key][] = $value;
    $output[$key][] = $arrTwo[$key];
  }
  else{
    $output[$key] = $value;
  }
}

$output += $arrTwo;    // To consider keys that were absent in $arrOne 
print_r($output);

?>

Check the output in http://codepad.org/FrIlKRqk

And the result

Array
(
[2009] => 131
[2008] => Array
    (
        [0] => 940
        [1] => 9
    )

[2007] => Array
    (
        [0] => 176
        [1] => 3
    )

[2006] => 1
[2011] => 67
)

Answer 5

Both arrays use the same keys, so you could do something simple like this (only works on one level though):

foreach ($array2 as $key => $value)
{
    $array1[$key][] = $value
}

Update:

$array3 = array()
foreach ($array1 as $key => $value)
{
    $array3[$key][] = $value
}
foreach ($array2 as $key => $value)
{
    $array3[$key][] = $value
}

Answer 6

probaly something like that? If you run such a loop for each Array (array1, array2,…)

$list = array()

foreach( $array1 as $key => $value ){
    if( !array_key_exist( $key, $array) ){
        $list[$key] = $value
    } else if( !is_array( $list[$key] ) ) {
        $list[$key] = array(list[$key])
    } else {
        array_push( $list[$key], $value );
    }
}

nb.: the code is not tested…

Answer 7

Try:

foreach ($your_array as $key => $value)
    $array_new[$key][] = $value;
print_r($array_new);

Answer 8

I see much answers but I dont find them usable so Im adding my own

function merge(){
    $args = func_get_args();
    $new = array();
    foreach($args as $arg){
        foreach($arg as $key => $item){
            if(!isset($new[$key])){
                $new[$key] = $item;
            }else if (!is_array($new[$key)){
                $new[$key] = array($new[$key],$item);
            }else{
                $new[$key][] = $item;
            }
        }
    }
    return $new;
}

You can put in unlimited arguments :)

Answer 9

I eventually found this function that helped me. Thank you everyone for your input.

function merge_common_keys()
{
    $arr  = func_get_args();
    $num  = func_num_args();
    $keys = array();
    $i    = 0;
    for ($i = 0; $i < $num; ++$i) {
        $keys = array_merge($keys, array_keys($arr[$i]));
    }
    $keys   = array_unique($keys);
    $merged = array();
    foreach ($keys as $key) {
        $merged[$key] = array();
        for ($i = 0; $i < $num; ++$i) {
            $merged[$key][] = isset($arr[$i][$key]) ? $arr[$i][$key] : null;
        }
    }
    return $merged;
}