I think the example given here using classes is convoluting things too much to demonstrate what this function does.
array_udiff() will walk through array_values($a) and array_values($b) and compare each value by using the passed in callback function.
To put it another way, array_udiff() compares $a[0] to $b[0], $b[1], $b[2], and $b[3] using the provided callback function. If the callback returns zero for any of the comparisons then $a[0] will not be in the returned array from array_udiff(). It then compares $a[1] to $b[0], $b[1], $b[2], and $b[3]. Then, finally, $a[2] to $b[0], $b[1], $b[2], and $b[3].
For example, compare_ids($a[0], $b[0]) === -5 while compare_ids($a[1], $b[1]) === 0. Therefore, $a[1] is not returned from array_udiff() since it is present in $b.
<?
$a = array(
array(
'id' => 10,
'name' => 'John',
'color' => 'red',
),
array(
'id' => 20,
'name' => 'Elise',
'color' => 'blue',
),
array(
'id' => 30,
'name' => 'Mark',
'color' => 'red',
),
);
$b = array(
array(
'id' => 15,
'name' => 'Nancy',
'color' => 'black',
),
array(
'id' => 20,
'name' => 'Elise',
'color' => 'blue',
),
array(
'id' => 30,
'name' => 'Mark',
'color' => 'red',
),
array(
'id' => 40,
'name' => 'John',
'color' => 'orange',
),
);
function compare_ids($a, $b)
{
return ($a['id'] - $b['id']);
}
function compare_names($a, $b)
{
return strcmp($a['name'], $b['name']);
}
$ret = array_udiff($a, $b, 'compare_ids');
var_dump($ret);
$ret = array_udiff($b, $a, 'compare_ids');
var_dump($ret);
$ret = array_udiff($a, $b, 'compare_names');
var_dump($ret);
?>
Which returns the following.
In the first return we see that $b has no entry in it with an id of 10.
<?
array(1) {
[0]=>
array(3) {
["id"]=>
int(10)
["name"]=>
string(4) "John"
["color"]=>
string(3) "red"
}
}
?>
In the second return we see that $a has no entry in it with an id of 15 or 40.
<?
array(2) {
[0]=>
array(3) {
["id"]=>
int(15)
["name"]=>
string(5) "Nancy"
["color"]=>
string(5) "black"
}
[3]=>
array(3) {
["id"]=>
int(40)
["name"]=>
string(4) "John"
["color"]=>
string(6) "orange"
}
}
?>
In third return we see that all names in $a are in $b (even though the entry in $b whose name is 'John' is different, the anonymous function is only comparing names).
<?
array(0) {
}
?>
array_udiff
(PHP 5, PHP 7)
array_udiff — 데이터 비교 콜백함수를 사용하여 배열간의 차이를 계산
설명
데이터 비교 콜백함수를 사용하여 배열간의 차이를 계산합니다. 데티터 비교에 내부함수를 사용하는 array_diff() 와는 다릅니다.
인수
-
array1 -
첫번째 배열.
-
array2 -
두번째 배열.
-
value_compare_func -
비교 콜백 함수.
이 비교 함수는 첫번째 인수가 두번째 인수보다 작거나, 같거나, 클 경우에 각각 0보다 작거나, 같거나, 큰 정수를 반환해야 합니다.
반환값
다른 배열 인자에 존재하지 않는 array1의 모든값을 리턴합니다.
예제
Example #1 stdClass 객체를 이용한 array_udiff() 예제
<?php
// 비교할 배열들
$array1 = array(new stdclass, new stdclass,
new stdclass, new stdclass,
);
$array2 = array(
new stdclass, new stdclass,
);
// 각각 오브젝트의 프로퍼티 마다 값 세팅.
$array1[0]->width = 11; $array1[0]->height = 3;
$array1[1]->width = 7; $array1[1]->height = 1;
$array1[2]->width = 2; $array1[2]->height = 9;
$array1[3]->width = 5; $array1[3]->height = 7;
$array2[0]->width = 7; $array2[0]->height = 5;
$array2[1]->width = 9; $array2[1]->height = 2;
function compare_by_area($a, $b) {
$areaA = $a->width * $a->height;
$areaB = $b->width * $b->height;
if ($areaA < $areaB) {
return -1;
} elseif ($areaA > $areaB) {
return 1;
} else {
return 0;
}
}
print_r(array_udiff($array1, $array2, 'compare_by_area'));
?>
위 예제의 출력:
Array
(
[0] => stdClass Object
(
[width] => 11
[height] => 3
)
[1] => stdClass Object
(
[width] => 7
[height] => 1
)
)
Example #2 DateTime 객체를 이용한 array_udiff() 예제
<?php
class MyCalendar {
public $free = array();
public $booked = array();
public function __construct($week = 'now') {
$start = new DateTime($week);
$start->modify('Monday this week midnight');
$end = clone $start;
$end->modify('Friday this week midnight');
$interval = new DateInterval('P1D');
foreach (new DatePeriod($start, $interval, $end) as $freeTime) {
$this->free[] = $freeTime;
}
}
public function bookAppointment(DateTime $date, $note) {
$this->booked[] = array('date' => $date->modify('midnight'), 'note' => $note);
}
public function checkAvailability() {
return array_udiff($this->free, $this->booked, array($this, 'customCompare'));
}
public function customCompare($free, $booked) {
if (is_array($free)) $a = $free['date'];
else $a = $free;
if (is_array($booked)) $b = $booked['date'];
else $b = $booked;
if ($a == $b) {
return 0;
} elseif ($a > $b) {
return 1;
} else {
return -1;
}
}
}
// 주간 스케쥴 달력 생성
$myCalendar = new MyCalendar;
// 이주의 스케쥴 예약
$myCalendar->bookAppointment(new DateTime('Monday this week'), "Cleaning GoogleGuy's apartment.");
$myCalendar->bookAppointment(new DateTime('Wednesday this week'), "Going on a snowboarding trip.");
$myCalendar->bookAppointment(new DateTime('Friday this week'), "Fixing buggy code.");
// 예약일 대비 가용일 체크
echo "I'm available on the following days this week...\n\n";
foreach ($myCalendar->checkAvailability() as $free) {
echo $free->format('l'), "\n";
}
echo "\n\n";
echo "I'm busy on the following days this week...\n\n";
foreach ($myCalendar->booked as $booked) {
echo $booked['date']->format('l'), ": ", $booked['note'], "\n";
}
?>
위 예제의 출력:
I'm available on the following days this week... Tuesday Thursday I'm busy on the following days this week... Monday: Cleaning GoogleGuy's apartment. Wednesday: Going on a snowboarding trip. Friday: Fixing buggy code.
주의
Note: 이 함수는 n차원 배열의 1차 배열만 체크하므로 주의하기 바랍니다. 물론 깊은 차원의 체크는 array_udiff($array1[0], $array2[0], "data_compare_func"); 로 가능합니다.
참고
- array_diff() - 배열 차이를 계산
- array_diff_assoc() - 추가적인 인덱스 확인과 함께 배열 차이를 계산
- array_diff_uassoc() - Computes the difference of arrays with additional index check which is performed by a user supplied callback function
- array_udiff_assoc() - Computes the difference of arrays with additional index check, compares data by a callback function
- array_udiff_uassoc() - Computes the difference of arrays with additional index check, compares data and indexes by a callback function
- array_intersect() - 배열의 교집합을 계산
- array_intersect_assoc() - 인덱스 검사과 함께 배열의 교집합을 계산
- array_uintersect() - Computes the intersection of arrays, compares data by a callback function
- array_uintersect_assoc() - Computes the intersection of arrays with additional index check, compares data by a callback function
- array_uintersect_uassoc() - Computes the intersection of arrays with additional index check, compares data and indexes by separate callback functions
add a note
User Contributed Notes 9 notes
Colin ¶
17 years ago
napcoder ¶
7 years ago
Note that the compare function is used also internally, to order the arrays and choose which element compare against in the next round.
If your compare function is not really comparing (ie. returns 0 if elements are equals, 1 otherwise), you will receive an unexpected result.
grantwparks at gmail dot com ¶
16 years ago
Re: "convoluted"
I think the point being made is that array_udiff() can be used not only for comparisons between homogenous arrays, as in your example (and definitely the most common need), but it can be used to compare heterogeneous arrays, too.
Consider:
<?php
function compr_1($a, $b) {
$aVal = is_array($a) ? $a['last_name'] : $a;
$bVal = is_array($b) ? $b['last_name'] : $b;
return strcasecmp($aVal, $bVal);
}
$aEmployees = array(
array('last_name' => 'Smith',
'first_name' => 'Joe',
'phone' => '555-1000'),
array('last_name' => 'Doe',
'first_name' => 'John',
'phone' => '555-2000'),
array('last_name' => 'Flagg',
'first_name' => 'Randall',
'phone' => '666-1000')
);
$aNames = array('Doe', 'Smith', 'Johnson');
$result = array_udiff($aEmployees, $aNames, "compr_1");
print_r($result);
?>
Allowing me to get the "employee" that's not in the name list:
Array ( [2] => Array ( [last_name] => Flagg [first_name] => Randall [phone] => 666-1000 ) )
Something interesting to note, is that the two arguments to the compare function don't correspond to array1 and array2. That's why there has to be logic in it to handle that either of the arguments might be pointing to the more complex employee array. (Found this out the hard way.)
adam dot jorgensen dot za at gmail dot com ¶
15 years ago
It is not stated, by this function also diffs array1 to itself, removing any duplicate values...
b4301775 at klzlk dot com ¶
12 years ago
Quick example for using array_udiff to do a multi-dimensional diff
Returns values of $arr1 that are not in $arr2
<?php
$arr1 = array( array('Bob', 42), array('Phil', 37), array('Frank', 39) );
$arr2 = array( array('Phil', 37), array('Mark', 45) );
$arr3 = array_udiff($arr1, $arr2, create_function(
'$a,$b',
'return strcmp( implode("", $a), implode("", $b) ); ')
);
print_r($arr3);
?>
Output:
Array
(
[0] => Array
(
[0] => Bob
[1] => 42
)
[2] => Array
(
[0] => Frank
[1] => 39
)
)
1
Hope this helps someone
Jorge Morales (morales2k) ¶
5 years ago
I find it that this is an ideal place to apply the spaceship operator, but it was not used in the examples.
Here is Example#1 using the spaceship operator in the comparison function.
<?php
// Arrays to compare
$array1 = array(new stdclass, new stdclass,
new stdclass, new stdclass,
);
$array2 = array(
new stdclass, new stdclass,
);
// Set some properties for each object
$array1[0]->width = 11; $array1[0]->height = 3;
$array1[1]->width = 7; $array1[1]->height = 1;
$array1[2]->width = 2; $array1[2]->height = 9;
$array1[3]->width = 5; $array1[3]->height = 7;
$array2[0]->width = 7; $array2[0]->height = 5;
$array2[1]->width = 9; $array2[1]->height = 2;
function compare_by_area($a, $b) {
$areaA = $a->width * $a->height;
$areaB = $b->width * $b->height;
return $areaA <=> $areaB;
}
print_r(array_udiff($array1, $array2, 'compare_by_area'));
?>
The output is:
Array
(
[0] => stdClass Object
(
[width] => 11
[height] => 3
)
[1] => stdClass Object
(
[width] => 7
[height] => 1
)
)
I find it is pretty awesome you can substitute all of these lines:
if ($areaA < $areaB) {
return -1;
} elseif ($areaA > $areaB) {
return 1;
} else {
return 0;
}
with just:
return $areaA <=> $areaB;
Neat!
dmhouse at gmail dot com ¶
19 years ago
Very easy way of achieving a case-insensitive version of array_diff (or indeed array_diff_assoc, array_intersect or any of these types of functions which have a similar function that takes a callback function as one of their parameters):
array_udiff($array1, $array2, 'strcasecmp');
This works because strcasecmp() compares two strings case-insensitively, as compared to the array_diff() which compares two strings by using the == operator, which is case-sensitive.
jared ¶
14 years ago
Note that php does the string conversion *before* sending the values to the callback function.
aidan at php dot net ¶
19 years ago
This functionality is now implemented in the PEAR package PHP_Compat.
More information about using this function without upgrading your version of PHP can be found on the below link:
http://pear.php.net/package/PHP_Compat
