A simple trick that can help you to guess what diff/intersect or sort function does by name.
[suffix] assoc - additional index check. Compares both value and index.
Example: array_diff_assoc, array_intersect_assoc.
[suffix] key - index only check. Ignores value of array, compares only indexes.
Example: array_diff_key, array_intersect_key.
[suffix] **empty** - no "key" or "assoc" word in suffix. Compares values only. Ignores indexes of array.
Example: array_diff, array_intersect.
[prefix] u - will do comparison with user defined function. Letter u can be used twice in some functions (like array_udiff_uassoc), this means that you have to use 2 functions (one for value, one for index).
Example: array_udiff_uassoc, array_uintersect_assoc.
This also works with array sort functions:
[prefix] a - associative. Will preserve keys.
Example: arsort, asort.
[prefix] k - key sort. Will sort array by keys.
Example: uksort, ksort.
[prefix] r - reverse. Will sort array in reverse order.
Example: rsort, krsort.
[prefix] u - sort by user defined function (same as for diff/intersect).
Example: usort, uasort.
Array Functions
See Also
See also is_array(), explode(), implode(), preg_split(), and unset().
Table of Contents
- array_change_key_case — Changes the case of all keys in an array
- array_chunk — Split an array into chunks
- array_column — Return the values from a single column in the input array
- array_combine — Creates an array by using one array for keys and another for its values
- array_count_values — Counts the occurrences of each distinct value in an array
- array_diff_assoc — Computes the difference of arrays with additional index check
- array_diff_key — Computes the difference of arrays using keys for comparison
- array_diff_uassoc — Computes the difference of arrays with additional index check which is performed by a user supplied callback function
- array_diff_ukey — Computes the difference of arrays using a callback function on the keys for comparison
- array_diff — Computes the difference of arrays
- array_fill_keys — Fill an array with values, specifying keys
- array_fill — Fill an array with values
- array_filter — Filters elements of an array using a callback function
- array_flip — Exchanges all keys with their associated values in an array
- array_intersect_assoc — Computes the intersection of arrays with additional index check
- array_intersect_key — Computes the intersection of arrays using keys for comparison
- array_intersect_uassoc — Computes the intersection of arrays with additional index check, compares indexes by a callback function
- array_intersect_ukey — Computes the intersection of arrays using a callback function on the keys for comparison
- array_intersect — Computes the intersection of arrays
- array_is_list — Checks whether a given array is a list
- array_key_exists — Checks if the given key or index exists in the array
- array_key_first — Gets the first key of an array
- array_key_last — Gets the last key of an array
- array_keys — Return all the keys or a subset of the keys of an array
- array_map — Applies the callback to the elements of the given arrays
- array_merge_recursive — Merge one or more arrays recursively
- array_merge — Merge one or more arrays
- array_multisort — Sort multiple or multi-dimensional arrays
- array_pad — Pad array to the specified length with a value
- array_pop — Pop the element off the end of array
- array_product — Calculate the product of values in an array
- array_push — Push one or more elements onto the end of array
- array_rand — Pick one or more random keys out of an array
- array_reduce — Iteratively reduce the array to a single value using a callback function
- array_replace_recursive — Replaces elements from passed arrays into the first array recursively
- array_replace — Replaces elements from passed arrays into the first array
- array_reverse — Return an array with elements in reverse order
- array_search — Searches the array for a given value and returns the first corresponding key if successful
- array_shift — Shift an element off the beginning of array
- array_slice — Extract a slice of the array
- array_splice — Remove a portion of the array and replace it with something else
- array_sum — Calculate the sum of values in an array
- array_udiff_assoc — Computes the difference of arrays with additional index check, compares data by a callback function
- array_udiff_uassoc — Computes the difference of arrays with additional index check, compares data and indexes by a callback function
- array_udiff — Computes the difference of arrays by using a callback function for data comparison
- array_uintersect_assoc — Computes the intersection of arrays with additional index check, compares data by a callback function
- array_uintersect_uassoc — Computes the intersection of arrays with additional index check, compares data and indexes by separate callback functions
- array_uintersect — Computes the intersection of arrays, compares data by a callback function
- array_unique — Removes duplicate values from an array
- array_unshift — Prepend one or more elements to the beginning of an array
- array_values — Return all the values of an array
- array_walk_recursive — Apply a user function recursively to every member of an array
- array_walk — Apply a user supplied function to every member of an array
- array — Create an array
- arsort — Sort an array in descending order and maintain index association
- asort — Sort an array in ascending order and maintain index association
- compact — Create array containing variables and their values
- count — Counts all elements in an array or in a Countable object
- current — Return the current element in an array
- each — Return the current key and value pair from an array and advance the array cursor
- end — Set the internal pointer of an array to its last element
- extract — Import variables into the current symbol table from an array
- in_array — Checks if a value exists in an array
- key_exists — Alias of array_key_exists
- key — Fetch a key from an array
- krsort — Sort an array by key in descending order
- ksort — Sort an array by key in ascending order
- list — Assign variables as if they were an array
- natcasesort — Sort an array using a case insensitive "natural order" algorithm
- natsort — Sort an array using a "natural order" algorithm
- next — Advance the internal pointer of an array
- pos — Alias of current
- prev — Rewind the internal array pointer
- range — Create an array containing a range of elements
- reset — Set the internal pointer of an array to its first element
- rsort — Sort an array in descending order
- shuffle — Shuffle an array
- sizeof — Alias of count
- sort — Sort an array in ascending order
- uasort — Sort an array with a user-defined comparison function and maintain index association
- uksort — Sort an array by keys using a user-defined comparison function
- usort — Sort an array by values using a user-defined comparison function
add a note
User Contributed Notes 13 notes
permanovd at gmail dot com ¶
6 years ago
renatonascto at gmail dot com ¶
16 years ago
Big arrays use a lot of memory possibly resulting in memory limit errors. You can reduce memory usage on your script by destroying them as soon as you´re done with them. I was able to get over a few megabytes of memory by simply destroying some variables I didn´t use anymore.
You can view the memory usage/gain by using the funcion memory_get_usage(). Hope this helps!
indioeuropeo at driverop dot com ¶
5 years ago
I need to take an element from the Array and change its position within the Array by moving the rest of the elements as required.
This is the function that does it. The first parameter is the working Array. The second is the position of the element to move and the third is the position where to move the element.
The function returns the modified Array.
<?php
function array_move_elem($array, $from, $to) {
if ($from == $to) { return $array; }
$c = count($array);
if (($c > $from) and ($c > $to)) {
if ($from < $to) {
$f = $array[$from];
for ($i = $from; $i < $to; $i++) {
$array[$i] = $array[$i+1];
}
$array[$to] = $f;
} else {
$f = $array[$from];
for ($i = $from; $i > $to; $i--) {
$array[$i] = $array[$i-1];
}
$array[$to] = $f;
}
}
return $array;
}
?>
Examples:
<?php
$array = array('Cero','Uno','Dos','Tres','Cuatro','Cinco','Seis','Siete','Ocho','Nueve','Diez');
$array = array_move_elem($array, 3, 5); // Move element in position 3 to position 5...
print_r($array);
$array = array_move_elem($array, 5, 3); // Move element in position 5 to position 3, leaving array as it was... ;)
print_r($array);
?>
Return:
<?php
Array ( [0] => Cero [1] => Uno [2] => Dos [3] => Cuatro [4] => Cinco [5] => Tres [6] => Seis [7] => Siete [8] => Ocho [9] => Nueve [10] => Diez )
Array ( [0] => Cero [1] => Uno [2] => Dos [3] => Tres [4] => Cuatro [5] => Cinco [6] => Seis [7] => Siete [8] => Ocho [9] => Nueve [10] => Diez )
?>
ob at babcom dot biz ¶
18 years ago
Here is a function to find out the maximum depth of a multidimensional array.
<?php
// return depth of given array
// if Array is a string ArrayDepth() will return 0
// usage: int ArrayDepth(array Array)
function ArrayDepth($Array,$DepthCount=-1,$DepthArray=array()) {
$DepthCount++;
if (is_array($Array))
foreach ($Array as $Key => $Value)
$DepthArray[]=ArrayDepth($Value,$DepthCount);
else
return $DepthCount;
foreach($DepthArray as $Value)
$Depth=$Value>$Depth?$Value:$Depth;
return $Depth;
}
?>
info at hotkey404 dot com ¶
4 years ago
Updated code of 'indioeuropeo' with option to input string-based keys.
INPUT:
array(4) {
["a"]=>
string(5) "Apple"
["b"]=>
string(6) "Banana"
["c"]=>
string(3) "Cat"
["d"]=>
string(3) "Dog"
}
OUTPUT:
array(4) {
["a"]=>
string(5) "Apple"
["d"]=>
string(3) "Dog"
["b"]=>
string(6) "Banana"
["c"]=>
string(3) "Cat"
}
FUNCTION:
<?php
function array_move_elem($array, $from, $to){
// return if non-numeric couldn't be found or from=to
if(!is_numeric($from)){
if(array_search($from, array_keys($array))!==FALSE){
$from = array_search($from, array_keys($array));
}else{
return $array;
}
}
$array_numeric_keys = array();
foreach($array as $k => $v){
$array_numeric_keys[] = $k;
}
if ($from == $to) { return $array; }
$c = count($array_numeric_keys);
if (($c > $from) and ($c > $to)) {
if ($from < $to) {
$f = $array_numeric_keys[$from];
for ($i = $from; $i < $to; $i++) {
$array_numeric_keys[$i] = $array_numeric_keys[$i+1];
}
$array_numeric_keys[$to] = $f;
} else {
$f = $array_numeric_keys[$from];
for ($i = $from; $i > $to; $i--) {
$array_numeric_keys[$i] = $array_numeric_keys[$i-1];
}
$array_numeric_keys[$to] = $f;
}
}
$array_new = array();
foreach($array_numeric_keys as $v){
$array_new[$v] = $array[$v];
}
return $array_new;
}
?>
kolkabes at googlemail dot com ¶
12 years ago
Short function for making a recursive array copy while cloning objects on the way.
<?php
function arrayCopy( array $array ) {
$result = array();
foreach( $array as $key => $val ) {
if( is_array( $val ) ) {
$result[$key] = arrayCopy( $val );
} elseif ( is_object( $val ) ) {
$result[$key] = clone $val;
} else {
$result[$key] = $val;
}
}
return $result;
}
?>
dave at davidhbrown dot us ¶
13 years ago
While PHP has well over three-score array functions, array_rotate is strangely missing as of PHP 5.3. Searching online offered several solutions, but the ones I found have defects such as inefficiently looping through the array or ignoring keys.
The following array_rotate() function uses array_merge and array_shift to reliably rotate an array forwards or backwards, preserving keys. If you know you can trust your $array to be an array and $shift to be between 0 and the length of your array, you can skip the function definition and use just the return expression in your code.
<?php
function array_rotate($array, $shift) {
if(!is_array($array) || !is_numeric($shift)) {
if(!is_array($array)) error_log(__FUNCTION__.' expects first argument to be array; '.gettype($array).' received.');
if(!is_numeric($shift)) error_log(__FUNCTION__.' expects second argument to be numeric; '.gettype($shift)." `$shift` received.");
return $array;
}
$shift %= count($array); //we won't try to shift more than one array length
if($shift < 0) $shift += count($array);//handle negative shifts as positive
return array_merge(array_slice($array, $shift, NULL, true), array_slice($array, 0, $shift, true));
}
?>
A few simple tests:
<?php
$array=array("foo"=>1,"bar"=>2,"baz"=>3,4,5);
print_r(array_rotate($array, 2));
print_r(array_rotate($array, -2));
print_r(array_rotate($array, count($array)));
print_r(array_rotate($array, "4"));
print_r(array_rotate($array, -9));
?>
nicoolasens at gmail dot com ¶
9 years ago
/*to change an index without rewriting the whole table and leave at the same place.
*/
<?php
function change_index(&$tableau, $old_key, $new_key) {
$changed = FALSE;
$temp = 0;
foreach ($tableau as $key => $value) {
switch ($changed) {
case FALSE :
//creates the new key and deletes the old
if ($key == $old_key) {
$tableau[$new_key] = $tableau[$old_key];
unset($tableau[$old_key]);
$changed = TRUE;
}
break;
case TRUE :
//moves following keys
if ($key != $new_key){
$temp= $tableau[$key];
unset($tableau[$key]);
$tableau[$key] = $temp;
break;
}
else {$changed = FALSE;} //stop
}
}
array_values($tableau); //free_memory
}
//Result :
$tableau = array(1, 2 , 3, 4,5, 6, 7, 8, 9, 10);
$res = print_r($tableau, TRUE);
$longueur = strlen($res) -1;
echo "Old array :\n" . substr($res, 8, $longueur) . "\n" ;
change_index ($tableau, 2, 'number 2');
$res = print_r($tableau, TRUE);
$longueur = strlen($res) -10;
echo "New array :\n" . substr($res, 8, $longueur) . "\n" ;
/*
Old array :
[0] => 1
[1] => 2
[2] => 3
[3] => 4
[4] => 5
[5] => 6
[6] => 7
[7] => 8
[8] => 9
[9] => 10
)
New array :
[0] => 1
[1] => 2
[numéro 2] => 3
[3] => 4
[4] => 5
[5] => 6
[6] => 7
[7] => 8
[8] => 9
[9] => 10
*/
?>
Ewan ¶
7 years ago
I was looking for an array aggregation function here and ended up writing this one.
Note: This implementation assumes that none of the fields you're aggregating on contain The '@' symbol.
<?php
function array_group_by($flds, $arr) {
$groups = array();
foreach ($arr as $rec) {
$keys = array_map(function($f) use($rec) { return $rec[$f]; }, $flds);
$k = implode('@', $keys);
if (isset($groups[$k])) {
$groups[$k][] = $rec;
} else {
$groups[$k] = array($rec);
}
}
return $groups;
}
?>
DamianKaelGreen at gmail dot com ¶
7 years ago
While there are a lot of array functions in the PHP libs, there also seem to be a lot of rudimentary ones missing.
I went ahead and created several of my own functions for handling multiple non-associative (na) arrays including:
na_array_merge
na_array_intersect
na_array_diff
na_array_xnor
na_array_xor
If you are using Venn diagrams to think about your arrays, then these functions might be for you.
I have made them available and posted documentation for them here: https://www.greendingle.com/some-useful-non-associative-array-functions/
oliverSPAMMENOT at e-geek dot com dot au ¶
14 years ago
Function to pretty print arrays and objects. Detects object recursion and allows setting a maximum depth. Based on arraytostring and u_print_r from the print_r function notes. Should be called like so:
<?php
egvaluetostring($value) //no max depth, or
egvaluetostring($value, $max_depth) //max depth set
function egvaluetostring($value, $max_depth, $key = NULL, $depth = 0, $refChain = array()) {
if($depth > 0)
$tab = str_repeat("\t", $depth);
$text .= $tab . ($key !== NULL ? $key . " => " : "");
if (is_array($value) || is_object($value)) {
$recursion = FALSE;
if (is_object($value)) {
foreach ($refChain as $refVal) {
if ($refVal === $value) {
$recursion = TRUE;
break;
}
}
array_push($refChain, $value);
}
$text .= (is_array($value) ? "array" : "object") . " ( ";
if ($recursion) {
$text .= "*RECURSION* ";
}
elseif (isset($max_depth) && $depth >= $max_depth) {
$text .= "*MAX DEPTH REACHED* ";
}
else {
if (!empty($value)) {
$text .= "\n";
foreach ($value as $child_key => $child_value) {
$text .= egvaluetostring($child_value, $max_depth, (is_array($value) ? "[" : "") . $child_key . (is_array($value) ? "]" : ""), $depth+1, $refChain) . ",\n";
}
$text .= "\n" . $tab;
}
}
$text .= ")";
if (is_object($value)) {
array_pop($refChain);
}
}
else {
$text .= "$value";
}
return $text;
}
?>
mo dot longman at gmail dot com ¶
17 years ago
to 2g4wx3:
i think better way for this is using JSON, if you have such module in your PHP. See json.org.
to convert JS array to JSON string: arr.toJSONString();
to convert JSON string to PHP array: json_decode($jsonString);
You can also stringify objects, numbers, etc.
cyberchrist at futura dot net ¶
17 years ago
Lately, dealing with databases, I've been finding myself needing to know if one array, $a, is a proper subset of $b.
Mathematically, this is asking (in set theory) [excuse the use of u and n instead of proper Unicode):
( A u B ) n ( ~ B )
What this does is it first limits to known values, then looks for anything outside of B but in the union of A and B (which would be those things in A which are not also in B).
If any value exists in this set, then A is NOT a proper subset of B, because a value exists in A but not in B. For A to be a proper subset, all values in A must be in B.
I'm sure this could easily be done any number of ways but this seems to work for me. It's not got a lot of error detection such as sterilizing inputs or checking input types.
// bool array_subset( array, array )
// Returns true if $a is a proper subset of $b, returns false otherwise.
function array_subset( $a, $b )
{
if( count( array_diff( array_merge($a,$b), $b)) == 0 )
return true;
else
return false;
}
