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array_merge
array_merge & Fusionne plusieurs tableaux en un seul
Description
array array_merge
( array $array1
[, array $...
Si les tableaux d'entrées ont des clés en commun, alors,
la valeur finale pour cette clé écrasera la précédente. Cependant,
si les tableaux contiennent des clés numériques, la valeur
finale n'écrasera pas la valeur
originale, mais sera ajoutée.
Les clés numériques des tableaux d'entrées seront
renumérotées en clés incrémentées partant de zéro dans le tableau
résultat.
Liste de paramètres
Tableau initial à fusionner.
Liste de tableaux à fusionner.
Valeurs de retour
Retourne le tableau résultant.
Exemple #1 Exemple avec array_merge()
&?php$array1&=&array("color"&=&&"red",&2,&4);$array2&=&array("a",&"b",&"color"&=&&"green",&"shape"&=&&"trapezoid",&4);$result&=&array_merge($array1,&$array2);print_r($result);?&
L'exemple ci-dessus va afficher :
[color] =& green
[shape] =& trapezoid
Exemple #2 Exemple simple avec array_merge()
&?php$array1&=&array();$array2&=&array(1&=&&"data");$result&=&array_merge($array1,&$array2);?&
N'oubliez pas que les index numériques seront réindexés !
[0] =& data
Si vous voulez ajouter des éléments du second tableau au premier
sans pour autant écraser ou ré-indexer les éléments du premier,
utilisez l'opérateur d'union + :
&?php$array1&=&array(0&=&&'zero_a',&2&=&&'two_a',&3&=&&'three_a');$array2&=&array(1&=&&'one_b',&3&=&&'three_b',&4&=&&'four_b');$result&=&$array1&+&$array2;var_dump($result);?&
Les clés du premier tableau sont préservées. Si une clé existe
dans les 2 tableaux, alors l'élément du premier sera utilisé
et la clé correspondante du second sera ignorée.
array(5) {
string(6) &zero_a&
string(5) &two_a&
string(7) &three_a&
string(5) &one_b&
string(6) &four_b&
Exemple #3 Exemple avec array_merge() avec des types non-tableaux
&?php$beginning&=&'foo';$end&=&array(1&=&&'bar');$result&=&array_merge((array)$beginning,&(array)$end);print_r($result);?&
L'exemple ci-dessus va afficher :
[0] =& foo
[1] =& bar
Voir aussi
- Combine plusieurs tableaux ensemble, r&cursivement
- Remplace les &l&ments d'un tableau par ceux d'autres tableaux
- Cr&e un tableau & partir de deux autres tableaux
In some situations, the union operator ( + ) might be more useful to you than array_merge.& The array_merge function does not preserve numeric key values.& If you need to preserve the numeric keys, then using + will do that.ie:&?php$array1[0] = "zero";$array1[1] = "one";$array2[1] = "one";$array2[2] = "two";$array2[3] = "three";$array3 = $array1 + $array2;$array3 = array(0=&"zero", 1=&"one", 2=&"two", 3=&"three");?&Note the implicit "array_unique" that gets applied as well.& In some situations where your numeric keys matter, this behaviour could be useful, and better than array_merge.--Julian
As has already been noted before, reindexing arrays is most cleanly performed by the array_values() function.
to get unique value from multi dimensional array use this instead of array_unique(), because array_unique() does not work on multidimensional:array_map("unserialize", array_unique(array_map("serialize", $array)));Hope thExample$a=array(array('1'),array('2'),array('3'),array('4));$b=array(array('2'),array('4'),array('6'),array('8));$c=array_merge($a,$b);then write this line to get unique values$c=array_map("unserialize", array_unique(array_map("serialize", $c)));print_r($c);
Reiterating the notes about casting to arrays, be sure to cast if one of the arrays might be null:&?phpheader("Content-type:text/plain");$a = array('zzzz', 'xxxx');$b = array('mmmm','nnnn');echo "1 ==============\r\n";print_r(array_merge($a, $b));echo "2 ==============\r\n";$b = array();print_r(array_merge($a, $b));echo "3 ==============\r\n";$b = null;print_r(array_merge($a, $b));echo "4 ==============\r\n";$b = null;print_r(array_merge($a, (array)$b));echo "5 ==============\r\n";echo is_null(array_merge($a, $b)) ? 'Result is null' : 'Result is not null';?&Produces:1 ==============Array(& & [0] =& zzzz& & [1] =& xxxx& & [2] =& mmmm& & [3] =& nnnn)2 ==============Array(& & [0] =& zzzz& & [1] =& xxxx)3 ==============4 ==============Array(& & [0] =& zzzz& & [1] =& xxxx)5 ==============Result is null
if you generate form select from an array, you probably want to keep your array keys and order intact,if so you can use ArrayMergeKeepKeys(), works just like array_merge :array ArrayMergeKeepKeys ( array array1 [, array array2 [, array ...]])but keeps the keys even if of numeric kind. enjoy&?$Default[0]='Select Something please';$Data[147]='potato';$Data[258]='banana';$Data[54]='tomato';$A=array_merge($Default,$Data);$B=ArrayMergeKeepKeys($Default,$Data);echo '&pre&';print_r($A);print_r($B);echo '&/pre&';Function ArrayMergeKeepKeys() {& & & $arg_list = func_get_args();& & & foreach((array)$arg_list as $arg){& & & & & foreach((array)$arg as $K =& $V){& & & & & & & $Zoo[$K]=$V;& & & & & }& & & }& & return $Z}//will output :Array(& & [0] =& Select Something please& & [1] =& potato& & [2] =& banana& & [3] =& tomato)Array(& & [0] =& Select Something please& & [147] =& potato& & [258] =& banana& & [54] =& tomato)?&
We noticed array_merge is relatively slower than manually extending an array:given:$arr_one[ 'x' =& 1, 'y' =& 2 ];$arr_two[ 'a' =& 10, 'b' =& 20 ];the statement:$arr_three = array_merge( $arr_one, $arr_two );is routinely 200usec slower than:$arr_three = $arr_foreach( $arr_two as $k =& $v ) { $arr_three[ $k ] = $v; }200usec didn't matter...until we started combining huge arrays.PHP 5.6.x
An addition to what Julian Egelstaff above wrote - the array union operation (+) is not doing an array_unique - it will just not use the keys that are already defined in the left array.& The difference between union and merge can be seen in an example like this:&?php$arr1['one'] = 'one';$arr1['two'] = 'two';$arr2['zero'] = 'zero';$arr2['one'] = 'three';$arr2['two'] = 'four';$arr3 = $arr1 + $arr2;var_export( $arr3 );$arr4 = array_merge( $arr1, $arr2 );var_export( $arr4 );?&
to merge arrays and preserve the key i found the following working with php 4.3.1:
&?php
$array1 = array(1 =& "Test1", 2 =& "Test2");
$array2 = array(3 =& "Test3", 4 =& "Test4");
$array1 += $array2;
?&
dont know if this is working with other php versions but it is a simple and fast way to solve that problem.
I needed a function similar to ian at fuzzygroove's array_interlace, but I need to pass more than two arrays.
Here's my version, You can pass any number of arrays and it will interlace and key them properly.
&?php
function array_interlace() {
& & $args = func_get_args();
& & $total = count($args);
& & if($total & 2) {
& & & & return FALSE;
& & }
& &
& & $i = 0;
& & $j = 0;
& & $arr = array();
& &
& & foreach($args as $arg) {
& & & & foreach($arg as $v) {
& & & & & & $arr[$j] = $v;
& & & & & & $j += $total;
& & & & }
& & & &
& & & & $i++;
& & & & $j = $i;
& & }
& &
& & ksort($arr);
& & return array_values($arr);
}
?&
Example usage:
&?php
$a = array('a', 'b', 'c', 'd');
$b = array('e', 'f', 'g');
$c = array('h', 'i', 'j');
$d = array('k', 'l', 'm', 'n', 'o');
print_r(array_interlace($a, $b, $c, $d));
?&
Array
(
& & [0] =& a
& & [1] =& e
& & [2] =& h
& & [3] =& k
& & [4] =& b
& & [5] =& f
& & [6] =& i
& & [7] =& l
& & [8] =& c
& & [9] =& g
& & [10] =& j
& & [11] =& m
& & [12] =& d
& & [13] =& n
& & [14] =& o
)
Let me know if you improve on it.
Similar to Jo I had a problem merging arrays (thanks for that Jo you kicked me out of my debugging slumber) - array_merge does NOT act like array_push, as I had anticipated&?php$array = array('1', 'hello'); array_push($array, 'world');var_dump($array);$array = array('1', 'hello'); array_merge($array, array('world'));$array = array('1', 'hello'); $array = array_merge($array, array('world'));?&hope this helps someone
More on the union (+) operator:
the order of arrays is important and does not agree in my test below
with the other posts. The 'unique' operation preserves the initial key-value and discards later duplicates.
PHP 5.2.6-2ubuntu4.2
&?php
$a1=array('12345'=&'a', '23456'=&'b', '34567'=&'c', '45678'=&'d');
$a2=array('34567'=&'X');
$a3=$a1 + $a2;
$a4=$a2 + $a1;
print('a1:'); print_r($a1);
print('a2:'); print_r($a2);
print('a3:'); print_r($a3);
print('a4:'); print_r($a4);
?&
a1:Array
(
& & [12345] =& a
& & [23456] =& b
& & [34567] =& c
& & [45678] =& d
)
a2:Array
(
& & [34567] =& X
)
a3:Array
(
& & [12345] =& a
& & [23456] =& b
& & [34567] =& c
& & [45678] =& d
)
a4:Array
(
& & [34567] =& X
& & [12345] =& a
& & [23456] =& b
& & [45678] =& d
)
I keep seeing posts for people looking for a function to replace numeric keys.
No function is required for this, it is default behavior if the + operator:
&?php
$a=array(1=&"one", "two"=&2);
$b=array(1=&"two", "two"=&1, 3=&"three", "four"=&4);
print_r($a+$b);
?&
Array
(
& & [1] =& one
& & [two] =& 2
& & [3] =& three
& & [four] =& 4
)
How this works:
The + operator only adds unique keys to the resulting array.& By making the replacements the first argument, they naturally always replace the keys from the second argument, numeric or not! =)
More about the union operator (+)...The "array_unique" that gets applied, is actually based on the keys, not the values.& So if you have multiple values with the same key, only the last one will be preserved.&?php$array1[0] = "zero";$array1[1] = "one";$array2[0] = 0;$array1[1] = 1;$array3 = $array1 + $array2;?&
For those who are getting duplicate entries when using this function, there is a very easy solution:wrap array_unique() around array_merge()cheers,k.
WARNING: numeric subindexes are lost when merging arrays.Check this example:$a=array('abc'=&'abc','def'=&'def','123'=&'123','xyz'=&'xyz');echo "a=";print_r($a);$b=array('xxx'=&'xxx');echo "b=";print_r($b);$c=array_merge($a,$b);echo "c=";print_r($c);The result is this:c=Array(& & [abc] =& abc& & [def] =& def& & [0] =& 123& & [xyz] =& xyz& & [xxx] =& xxx)
The function behaves differently with numbers more than PHP_INT_MAX&?php$arr1 = array('9' =& 'dd');$arr2 = array('' =& 'ddd', '35' =& 'xxx');var_dump(array_merge($arr1, $arr2));$arr1 = array('1234' =& 'dd');$arr2 = array('12345' =& 'ddd', '35' =& 'xxx');var_dump(array_merge($arr1, $arr2));?&result:array(3) {& ["9"]=&& string(2) "dd"& [""]=&& string(3) "ddd"& [0]=&& string(3) "xxx"}array(3) {& [0]=&& string(2) "dd"& [1]=&& string(3) "ddd"& [2]=&& string(3) "xxx"}
Note that if you use + to merge array in order to preserve keys, that in case of duplicates the values from the left array in the addition is used.
In both PHP 4 and 5, array_merge preserves references in array values. For example:&?php$foo = 12;$array = array("foo" =& &$foo);$merged_array = array_merge($array, array("bar" =& "baz"));$merged_array["foo"] = 24;assert($foo === 24); ?&
array_merge will merge numeric keys in array iteration order, not in increasing numeric order. For example:
&?php
$a = array(0=&10, 1=&20);& $b = array(0=&30, 2=&50, 1=&40);
?&
array_merge($a, $b) will be array(10, 20, 30, 50, 40) and not array(10, 20, 30, 40, 50).
To combine several results (arrays):&?php$results = array(& & array(& & & & array('foo1'),& & & & array('foo2'),& & ),& & array(& & & & array('bar1'),& & & & array('bar2'),& & ),);$rows = call_user_func_array('array_merge', $results);print_r($rows);?&The above example will output:Array(& & [0] =& Array& & & & (& & & & & & [0] =& foo1& & & & )& & [1] =& Array& & & & (& & & & & & [0] =& foo2& & & & )& & [2] =& Array& & & & (& & & & & & [0] =& bar1& & & & )& & [3] =& Array& & & & (& & & & & & [0] =& bar2& & & & ))However, example below helps to preserve numeric keys:&?php$results = array(& & array(& & & & 123 =& array('foo1'),& & & & 456 =& array('foo2'),& & ),& & array(& & & & 321 =& array('bar1'),& & & & 654 =& array('bar2'),& & ),);$rows = array();foreach ($results as &$result) {& & $rows = $rows + $result; }print_r($rows);?&The above example will output:Array(& & [123] =& Array& & & & (& & & & & & [0] =& foo1& & & & )& & [456] =& Array& & & & (& & & & & & [0] =& foo2& & & & )& & [321] =& Array& & & & (& & & & & & [0] =& bar1& & & & )& & [654] =& Array& & & & (& & & & & & [0] =& bar2& & & & ))
I don't think that the comment on + operator for array in array_merge page, was understandable, this is just a little test to know exactly what's happend.&?php$a1 = array( '10', '11' , '12' , 'a' =& '1a', 'b' =& '1b');$a2 = array( '20', '21' , '22' , 'a' =& '2a', 'c' =& '2c');$a = $a1 + $a2;print_r( $a );$a = $a2 + $a1;print_r( $a );?&
It would seem that array_merge doesn't do anything when one array is empty (unset):&?php $b = array("1" =& "x");$a = array_merge($a, $b});?&to fix this omit $a if it is unset:-&?phpif(!IsSet($a)) {& & $a = array_merge($b);} else {& $a = array_merge($a, $b);}?&I don't know if there's a better way.
&?php& function array_deep_merge()& {& & switch( func_num_args() )& & {& & & case 0 : return false;& & & case 1 : return func_get_arg(0);& & & case 2 :& & & & $args = func_get_args();& & & & $args[2] = array();& & & & if( is_array($args[0]) and is_array($args[1]) )& & & & {& & & & & foreach( array_unique(array_merge(array_keys($args[0]),array_keys($args[1]))) as $key )& & & & & if( is_string($key) and is_array($args[0][$key]) and is_array($args[1][$key]) )& & & & & & $args[2][$key] = array_deep_merge( $args[0][$key], $args[1][$key] );& & & & & elseif( is_string($key) and isset($args[0][$key]) and isset($args[1][$key]) )& & & & & & $args[2][$key] = $args[1][$key];& & & & & elseif( is_integer($key) and isset($args[0][$key]) and isset($args[1][$key]) ) {& & & & & & $args[2][] = $args[0][$key]; $args[2][] = $args[1][$key]; }& & & & & elseif( is_integer($key) and isset($args[0][$key]) )& & & & & & $args[2][] = $args[0][$key];& & & & & elseif( is_integer($key) and isset($args[1][$key]) )& & & & & & $args[2][] = $args[1][$key];& & & & & elseif( ! isset($args[1][$key]) )& & & & & & $args[2][$key] = $args[0][$key];& & & & & elseif( ! isset($args[0][$key]) )& & & & & & $args[2][$key] = $args[1][$key];& & & & & return $args[2];& & & & }& & & & else return $args[1];& & & default :& & & & $args = func_get_args();& & & & $args[1] = array_deep_merge( $args[0], $args[1] );& & & & array_shift( $args );& & & & return call_user_func_array( 'array_deep_merge', $args );& & & && & }& }& $a = array(& & 0,& & array( 0 ),& & 'integer' =& 123,& & 'integer456_merge_with_integer444' =& 456,& & 'integer789_merge_with_array777' =& 789,& & 'array' =& array( "string1", "string2" ),& & 'array45_merge_with_array6789' =& array( "string4", "string5" ),& & 'arraykeyabc_merge_with_arraykeycd' =& array( 'a' =& "a", 'b' =& "b", 'c' =& "c" ),& & 'array0_merge_with_integer3' =& array( 0 ),& & 'multiple_merge' =& array( 1 ),& );& $b = array(& & 'integer456_merge_with_integer444' =& 444,& & 'integer789_merge_with_array777' =& array( 7,7,7 ),& & 'array45_merge_with_array6789' =& array( "string6", "string7", "string8", "string9" ),& & 'arraykeyabc_merge_with_arraykeycd' =& array( 'c' =& "ccc", 'd' =& "ddd" ),& & 'array0_merge_with_integer3' =& 3,& & 'multiple_merge' =& array( 2 ),& );& $c = array(& & 'multiple_merge' =& array( 3 ),& );& & echo "&pre&".htmlentities(print_r( array_deep_merge( $a, $b, $c ), true))."&/pre&";?&
Usage of operand '+' for merging arrays:&?php$a=array('a'=&'a1','b'=&'a2','a3','a4','a5');$b=array('b1','b2','a'=&'b3','b4');$a+=$b;print_r($a);?&output:Array(& & [a] =& a1& & [b] =& a2& & [0] =& a3& & [1] =& a4& & [2] =& a5& & [3] =& b5)numeric keys of elements of array B what not presented in array A was added.&?php$a=array('a'=&'a1','b'=&'a2','a3','a4','a5');$b=array(100=&'b1','b2','a'=&'b3','b4');$a+=$b;print_r($a);?&output:&& [a] =& a1& & [b] =& a2& & [0] =& a3& & [1] =& a4& & [2] =& a5& & [100] =& b1& & [101] =& b2& & [102] =& b4autoindex for array B started from 100, these keys not present in array A, so this elements was added to array A
i did a small benchmark (on& PHP 5.3.3) comparing:* using array_merge on numerically indexed arrays* using a basic double loop to merge multiple arraysthe performance difference is huge: &?phprequire_once("./lib/Timer.php");function method1($mat){& & $all=array();& & foreach($mat as $arr){& & & & $all=array_merge($all,$arr);& & }& & return $all;}function method2($mat){& & $all=array();& & foreach($mat as $arr){& & & & foreach($arr as $el){& & & & & & $all[]=$el;& & & & }& & }& & return $all;}function tryme(){& & $y=250; $x=200; $mat=array();& & for($i=0;$i&$y;$i++){& & & & for($j=0;$j&$x;$j++){& & & & & & $mat[$i][$j]=rand(0,1000);& & & & }& & & & }& & $t=new Timer();& & method1($mat);& & $t-&displayTimer();& & & & $t=new Timer();& & method2($mat);& & $t-&displayTimer();& & }tryme();?&So that's more than a factor 100!!!!!
Old behavior of array_merge can be restored by simple& variable type casting like thisarray_merge((array)$foo,(array)$bar);works good in php 5.1.0 Beta 1, not tested in other versions seems that empty or not set variables are casted to empty arrays
I have been searching for an in-place merge function, but couldn't find one. This function merges two arrays, but leaves the order untouched. Here it is for all others that want it:function inplacemerge($a, $b) {& $result = array();& $i = $j = 0;& if (count($a)==0) { return $b; }& if (count($b)==0) { return $a; }& while($i & count($a) && $j & count($b)){& & if ($a[$i] &= $b[$j]) {& & & $result[] = $a[$i];& & & if ($a[$i]==$b[$j]) { $j++; }& & & $i++;& & } else {& & & $result[] = $b[$j];& & & $j++;& & }& }& while ($i&count($a)){& & $result[] = $a[$i];& & $i++;& }& while ($j&count($b)){& & $result[] = $b[$j];& & $j++;& }& return $}
PHP is wonderfully decides if an array key could be a number, it is a number!& And thus wipes out the key when you array merge.&& Just a warning.$array1['4000'] = 'Grade 1 Widgets';$array1['4000a'] = 'Grade A Widgets';$array2['5830'] = 'Grade 1 Thing-a-jigs';$array2['HW39393'] = 'Some other widget';var_dump($array1);var_dump($array2);//results in...array(2) {& [4000]=&& string(15) "Grade 1 Widgets"& ["4000a"]=&& string(15) "Grade A Widgets"}array(2) {& [5830]=&& string(20) "Grade 1 Thing-a-jigs"& ["HW39393"]=&& string(17) "Some other widget"}var_dump(array_merge($array1,$array2));//results in...array(4) {& [0]=&& string(15) "Grade 1 Widgets"& ["4000a"]=&& string(15) "Grade A Widgets"& [1]=&& string(20) "Grade 1 Thing-a-jigs"& ["HW39393"]=&& string(17) "Some other widget"}
I found the "simple" method of adding arrays behaves differently as described in the documentation in PHP v5.2.0-10.$array1 + $array2 will only combine entries for keys that don't already exist.Take the following example:$ar1 = array('a', 'b');$ar2 = array('c', 'd');$ar3 = ($ar1 + $ar2);print_r($ar3);Result:Array(& & [0] =& a& & [1] =& b)Where as:$ar1 = array('a', 'b');$ar2 = array('c', 'd');$ar3 = array_merge($ar1, $ar2);print_r($ar3);Result:Array(& & [0] =& a& & [1] =& b& & [2] =& c& & [3] =& d)Hope this helps someone.
If you need to merge two arrays without having multiple entries, try this:&?phpfunction array_fusion($ArrayOne, $ArrayTwo){& & return array_unique(array_merge($ArrayOne, $ArrayTwo));}?&
It is not officially documented but it is summarily important information for everyone to know: neither array_merge or array_merge_recursive functions will function correctly if non-array objects& are used as parameters. You would probably expect these functions to ignore non-array elements, right? However, if one parameter is null it PHP will not only return null for the entire function but will also (not always) raise an error, such as :& & [ Warning: array_merge(): Argument #x is not an array... ]This error message won't appear if the defective variable is an empty array (an empty array is still an array), but it will result in an undesirable incomplete Array.There are several solutions for this problem by validating the Arrays before use them in these functions, but the most efficient way is to enforce the element as an array directly in the function itself. I.e.: $merged = array_merge( (array)$first_array, (array)$second_array );
I constantly forget the direction of array_merge so this is partially for me and partially for people like me.array_merge is a non-referential non-inplace right-reduction. For different ctrl-f typers, it's reduce-right, side-effect free, idempotent, and non in-place.ex:$a = array_merge(['k' =& 'a'], ['k' =& 'b']) =& ['k' =& 'b']array_merge(['z' =& 1], $a) =& does not modify $a but returns ['k' =& 'b', 'z' =& 1];Hopefully this helps people that constant look this up such as myself.
Sometimes you need to modify an array with another one here is my approach to replace an array's content recursively with delete opiton. Here i used "::delete::" as reserved word to delete items.&?php$person= array(& & "name" =& "Metehan",& & "surname"=&"Arslan",& & "age"=&27,& & "mail"=&"hidden",& & "favs" =& array(& & & & "language"=&"php",& & & & "planet"=&"mercury",& & & & "city"=&"istanbul"));$newdata = array(& & "age"=&28,& & "mail"=&"::delete::",& & "favs" =& array(& & & & "language"=&"js",& & & & "planet"=&"mercury",& & & & "city"=&"shanghai"));print_r(array_overlay($person,$newdata));function array_overlay($a1,$a2){& & foreach($a1 as $k =& $v) {& & & & if ($a2[$k]=="::delete::"){& & & & & & unset($a1[$k]);& & & & & && & & & };& & & & if(!array_key_exists($k,$a2))& & & & if(is_array($v) && is_array($a2[$k])){& & & & & & $a1[$k] = array_overlay($v,$a2[$k]);& & & & }else{& & & & & & $a1[$k] = $a2[$k];& & & & }& & & & & & }& & return $a1;}?&
As PHP 5.6 you can use array_merge + "splat" operator to reduce a bidimensonal array to a simple array:&?php$data = [[1, 2], [3], [4, 5]];print_r(array_merge(... $data)); ?&
public function mergeArrays($arrays, $field)& & {& & & & //take array in arrays for retrive structure after merging& & & & $clean_array = current($arrays);& & & & foreach ($clean_array as $i =& $value) {& & & & & & $clean_array[$i]='';& & & & }& & & & $merged_array = [];& & & & $name = '';& & & & foreach ($arrays as $array){& & & & & & $array = array_filter($array); //clean array from empty values& & & & & & if ($name == $array[$field]) {& & & & & & & & $merged_array[$name] = array_merge($merged_array[$name], $array);& & & & & & & & $name = $array[$field];& & & & & & } else {& & & & & & & & $name = $array[$field];& & & & & & & & $merged_array[$name] = $& & & & & & }& & & & }& & & & //have to be cleaned from array 'field' signs to return original structure of arrays& & & & foreach ($merged_array as $array){& & & & & & $ready_array[] = array_merge($clean_array, $array);& & & & }& & & & return $ready_& & }
be aware there is a slight difference:
&?php
$array1 = array('lang'=&'js','method'=&'GET');
$array2 = array('lang'=&'php','browser'=&'opera','method'=&'POST');
?&
&?php array_merge($array2,$array1); ?&
outputs: Array ( [lang] =& js [browser] =& opera [method] =& GET )
notice that the repeated keys will be overwritten by the ones of $array1, maintaining those, because it is the array that is being merged
&?php array_merge($array1,$array2); ?&
outputs: Array ( [lang] =& php [method] =& POST [browser] =& opera )
here the oposite takes place: array1 will have its elements replaced by those of array2.
Uniques values merge for array_merge function:
function array_unique_merge() {
& & & &
& & & & $variables = '$_'.implode(',$_',array_keys(func_get_args()));
& & & & $func = create_function('$tab', ' list('.$variables.') = $ return array_unique(array_merge('.$variables.'));');
& & & &
& & & & return $func(func_get_args());
& & }
?&
Doesn't work on objects.
Smarter way for uniques values merge array:
&?php
function array_unique_merge() {
& & &&
& & && return array_unique(call_user_func_array('array_merge', func_get_args()));
&& }
?&
Example 1:
$a = array(1,2);
$b = array(2,3,4);
array_unique_merge($a,$b);
Return:
array(1,2,3,4);
Example 2:
$a = array(1,2);
$b = array(2,3,4);
$c = array(2,3,4,5);
array_unique_merge($a,$b);
Return:
array(1,2,3,4,5);
Doesn't work on objects.
I had a hard time using array_merge with large datasets. By the time my web framework was in memory there wasn't enough space to have multiple copies of my dataset. To fix this I had to remove any functions which operated on the data set and made a copy in memory (pass by value). I realize the available memory to an application instance is modifiable, but I didn't think I should have to set it below the default 16mb for a web app!Unfortunately, a number of php functions pass by value internally, so I had to write my own merge function. This passes by reference, utilizes a fast while loop (thus doesn't need to call count() to get an upper boundary, also a php pass by value culprit), and unsets the copy array (freeing memory as it goes). &?phpfunction mergeArrays(&$sourceArray, &$copyArray){& & & & $i = 0;& & & & while (isset($copyArray[$i])){& & & & & & $sourceArray[] = $copyArray[$i];& & & & & & unset($copyArray[$i]);& & & & & & $i++;& & & & }& & }?&This fixed the problem. I would love to know if there is an even faster, more efficient way. Simply adding the two arrays won't work since there is an overlap of index.
Be ready to surprise like this one.array_merge renumbers numeric keys even if key is as string.keys '1' & '2' will be updated to 0 & 1, but '1.1' & '1.2' remain the same, but they are numeric too (is_numeric('1.1') -& true)It's better to use '+' operator or to have your own implementation for array_merge.&?php$x1 = array (& & '1'& && =& 'Value 1',& & '1.1'&& =& 'Value 1.1',);$x2 = array (& & '2'& && =& 'Value 2',& & '2.1'&& =& 'Value 2.1',);$x3 = array_merge( $x1, $x2 );echo '&pre&NOT as expected: '. print_r( $x3, true ) .'&/pre&';$x3 = $x1 + $x2;echo '&pre&As expected: '. print_r( $x3, true ) .'&/pre&';?&NOT as expected: Array(& & [0] =& Value 1& & [1.1] =& Value 1.1& & [1] =& Value 2& & [2.1] =& Value 2.1)As expected: Array(& & [1] =& Value 1& & [1.1] =& Value 1.1& & [2] =& Value 2& & [2.1] =& Value 2.1)
To avoid REINDEXING issues, use + operator :array_merge(& & & & & array("truc" =& "salut"),& & & & & array("machin" =& "coucou")& & & & )returns array(2){[0] =& string() "salut"[1] =& string() "coucou"}whereasarray("truc" =& "salut") + array("machin" =& "coucou")returnsarray(2){["truc"] =& string() "salut"["machin"] =& string() "coucou"}
Needed an quick array_merge clone that preserves the keys:
&?php
function array_join($a1, $a2, $a3=null, $a4=null, $a5=null, $a6=null, $a7=null, $a8=null, $a9=null, $a10=null) {
& & $a=array();
& & foreach($a1 as $key=&$value) $a[$key]=$value;
& & foreach($a2 as $key=&$value) $a[$key]=$value;
& & if (is_array($a3)) $a=array_join($a,$a3,$a4,$a5,$a6,$a7,$a8,$a9,$a10);
& & return $a;
}
?&
The documentation is a touch misleading when it says: "If only one array is given and the array is numerically indexed, the keys get reindexed in a continuous way."& Even with two arrays, the resulting array is re-indexed:[bishop@predator staging]$ cat array_merge.php &?php$a = array (23 =& 'Hello', '42' =& 'World');$a = array_merge(array (0 =& 'I say, '), $a);var_dump($a);?&[bishop@predator staging]$ php-5.2.5 array_merge.php array(3) {& [0]=&& string(7) "I say, "& [1]=&& string(5) "Hello"& [2]=&& string(5) "World"}[bishop@predator staging]$ php-4.4.7 array_merge.php array(3) {& [0]=&& string(7) "I say, "& [1]=&& string(5) "Hello"& [2]=&& string(5) "World"}
array_merge() overwrites ALL numerical indexes. No matter if you have non-numerical indexes or more than just one array.It reindexes them all. Period.(Only tried in 4.3.10)
For asteddy at tin dot it and others who are trying to merge arrays and keep the keys, don't forget the simple + operator.Using the array_merge_keys() function (with a small mod to deal with multiple arguments), provides no difference in output as compared to +.&?php$a = array(-1 =& 'minus 1');$b = array(0 =& 'nought');$c = array(0 =& 'nought');var_export(array_merge_keys($a,$b));var_export($a + $b);var_export(array_merge_keys($a,$b,$c));var_export($a + $b + $c);?&results in ...array (& -1 =& 'minus 1',& 0 =& 'nought',)array (& -1 =& 'minus 1',& 0 =& 'nought',)array (& -1 =& 'minus 1',& 0 =& 'nought',)array (& -1 =& 'minus 1',& 0 =& 'nought',)
The same result as produced by snookiex_at_gmail_dot_com's functioncan be achieved with the 'one-liner'&?php$array1=array(1,2,3);$array2=array('a','b','c');$matrix = array_map(null, $array1, $array2);?&(see documentation of array_map). The difference here is, that the shorter array gets filled with empty values.
An earlier comment mentioned that array_splice is faster than array_merge for inserting values. This may be the case, but if your goal is instead to reindex a numeric array, array_values() is the function of choice. Performing the following functions in a 100,000-iteration loop gave me the following times: ($b is a 3-element array)array_splice($b, count($b)) =& 0.410652$b = array_splice($b, 0) =& 0.272513array_splice($b, 3) =& 0.26529$b = array_merge($b) =& 0.233582$b = array_values($b) =& 0.151298
A more efficient array_merge that preserves keys, truly accepts an arbitrary number of arguments, and saves space on the stack (non recursive):&?phpfunction array_merge_keys(){& & $args = func_get_args();& & $result = array();& & foreach($args as &$array){& & & & foreach($array as $key=&&$value){& & & & & & $result[$key] = $value;& & & & }& & }& & return $result;}?&
You can use array_slice() in combination with array_merge() to insert values into an array like this:&?php$test=range(0, 10);$index=2;$data="---here---";$result=array_merge(array_slice($test, 0, $index), array($data), array_slice($test, $index));var_dump($result);?&
Do not use this to set the $_SESSION variable.$_SESSION = array_merge( $_SESSION, $another_array );will break your $_SESSION until the end of the execution of that page.
Note that if you put a number as a key in an array, it is eventually converted to an int even if you cast it to a string or put it in quotes.That is:$arr["0"] = "Test";var_dump( key($arr) );will output int(0).This is important to note when merging because array_merge will append values with a clashing int-based index instead of replacing them. This kept me tied up for hours.
Someone posted a function with the note:"if u need to overlay a array that holds defaultvalues with another that keeps the relevant data"&?//about twice as fast but the result is the same.//note: the sorting will be messed up!function array_overlay($skel, $arr) {& & return $arr+$}//example:$a = array("zero","one","two");$a = array_overlay($a,array(1=&"alpha",2=&NULL)); var_dump($a);/* NULL is ignored so the output is:array(3) {& [1]=&& string(5) "alpha"& [0]=&& string(4) "zero"& [2]=&& string(3) "two"}*/?&
I got tripped up for a few days when I tried to merge a (previously serialized) array into a object. If it doesn't make sense, think about it... To someone fairly new, it could... Anyway, here is what I did:(It's obviously not recursive, but easy to make that way)&?phpfunction array_object_merge(&$object, $array) {& & foreach ($array as $key =& $value)& & & & $object-&{$key} = $value;}?&Simple problem, but concevibly easy to get stuck on.
This function merges any number of arrays and maintains the keys:
&?php
function array_kmerge ($array) {
reset($array);
while ($tmp = each($array))
{
& if(count($tmp['value']) & 0)
& {
&& $k[$tmp['key']] = array_keys($tmp['value']);
&& $v[$tmp['key']] = array_values($tmp['value']);
& }
while($tmp = each($k))
{
& for ($i = $start; $i & $start+count($tmp['value']); $i ++)$r[$tmp['value'][$i-$start]] = $v[$tmp['key']][$i-$start];
& $start = count($tmp['value']);
return $r;
}
?&
I noticed the lack of a function that will safely merge two arrays without losing data due to duplicate keys but different values.So I wrote a quicky that would offset duplicate keys and thus preserve their data. of course, this does somewhat mess up association...&?php$array1=array('cats'=&'Murder the beasties!', 'ninjas'=&'Use Ninjas to murder cats!');$array2=array('cats'=&'Cats are fluffy! Hooray for Cats!', 'ninjas'=&'Ninas are mean cat brutalizers!!!');$array3=safe_array_merge($array1, $array2);print_r($array3)
There was a previous note that alluded to this, but at least in version 5.2.4 array_merge will return NULL if any of the arguments are NULL. This bit me with $_POST when none of the controls were successful.
While searching for a function that would renumber the keys in a array, I found out that array_merge() does this if the second parameter is null:
Starting with array $a like:
&?php
Array
(
& & [5] =& 5
& & [4] =& 4
& & [2] =& 2
& & [9] =& 9
)
?&
Then use array_merge() like this:
&?php
$a = array_merge($a, null);
?&
Now the $a array has bee renumbered, but maintaining the order:
&?php
Array
(
& & [0] =& 5
& & [1] =& 4
& & [2] =& 2
& & [3] =& 9
)
?&
Hope this helps someone :-)
Apparently there is a shorthand that works very much like array_merge. I figured I would leave a comment here, sense I saw it used in code but found nothing about it from google searches.&?php$array = array( 'name' =& 'John Doe');$array += array( 'address' =& 'someplace somestreet');echo $array['address']; ?&A difference from merge_array, it does NOT overwrite existing keys, regardless of key type.
The problem that the array keys are reindexed, and further not working on array values of type object or other mixed types.
Simply, I did this:
&?php
foreach($new as $k =& $v)
{
& & $old[$k] = $v;
}
?&
Please note that -1 is a numeric key and will be reindexed.Less obvious numeric keys are also '-1' (becomes -1) and -1.5 (becomes -1). '-1a', however, is not a numeric key and you could exploit the fact that '-1a' == -1 evaluates to true in php (just a hint). But as this is not very efficient, operator + may be a better option.&?php$arr = array(-1=& "-1", '-2'=& "'-2'", -3.5=& "-3.5", '-4a'=& "'-4a'");print_r(array(& & $arr,& & array_merge($arr,array()),& & '-1a' == -1,));?&Result:Array(& & [0] =& Array& & & & (& & & & & & [-1] =& -1& & & & & & [-2] =& '-2'& & & & & & [-3] =& -3.5& & & & & & [-4a] =& '-4a'& & & & )& & [1] =& Array& & & & (& & & & & & [0] =& -1& & & & & & [1] =& '-2'& & & & & & [2] =& -3.5& & & & & & [-4a] =& '-4a'& & & & )& & [2] =& 1)