php PHP中数组的集合理论联合

Set Theory Union of arrays in PHP

提问by Dmytro Zarezenko

There are 3 operations with sets in mathematics: intersection, difference and union (unification). In PHP we can do this operations with arrays:

数学中的集合有 3 种运算：交、差和并（统一）。在 PHP 中，我们可以对数组进行以下操作：

• intersection: array_intersect
• difference: array_diff

• 路口： array_intersect
• 区别： array_diff

What function is for union?

union 的作用是什么？

No duplicates can be in the result array (like array_intersectand array_diff).

结果数组中不能有重复项（如array_intersect和array_diff）。

If indexes are numeric then array_mergewill not overwrite the original value, but will be appended (PHP docs).

如果索引是数字，则array_merge不会覆盖原始值，但会附加（PHP 文档）。

回答by adrien

Try array_merge:

尝试array_merge：

array_unique(array_merge($array1, $array2));

PHP Manual

PHP 手册

回答by Brian

array_unique( array_merge( ... ) )

array_unique( array_merge( ... ) )

回答by Brilliand

Adrien's answer won't necessary produce a sequentially numbered array from two sequentially numbered arrays - here are some options that will:

Adrien 的答案不需要从两个按顺序编号的数组生成一个按顺序编号的数组 - 这里有一些选项可以：

array_values(array_unique(array_merge($array1, $array2)));

(Adrien's answer with renumbering the keys afterward)

（Adrien 的回答是之后对键重新编号）

array_keys(array_flip($array1)+array_flip($array2))

(Put the values in the keys, and use the array union operator)

（将值放在键中，并使用数组联合运算符）

array_merge($array1, array_diff($array2, $array1))

(Remove the shared values from the second array before merging)

（在合并之前从第二个数组中删除共享值）

Benchmark results (for merging two arrays of length 1000 a thousand times on my system):

基准测试结果（用于在我的系统上合并两个长度为 1000 的数组一千次）：

• Unique (Adrien's version): 2.862163066864 seconds
• Values_Unique: 3.12 seconds
• Keys_Flip: 2.34 seconds
• Merge_Diff: 2.64 seconds

• 唯一（Adrien 的版本）：2.862163066864 秒
• Values_Unique：3.12 秒
• Keys_Flip：2.34 秒
• Merge_Diff：2.64 秒

Same test, but with the two arrays being very similar (at least 80% duplicate):

相同的测试，但两个数组非常相似（至少 80% 重复）：

• Unique (Adrien's version): 2.92 seconds
• Values_Unique: 3.15 seconds
• Keys_Flip: 1.84 seconds
• Merge_Diff: 2.36 seconds

• 独特（Adrien 的版本）：2.92 秒
• Values_Unique：3.15 秒
• Keys_Flip：1.84 秒
• Merge_Diff：2.36 秒

It seems using the array union operator to do the actual union is the fastest method. Note however that array_flipis only safe if the array's values are all strings or all integers; if you have to produce the union of an array of objects, I recommend the version with array_mergeand array_diff.

似乎使用数组联合运算符进行实际联合是最快的方法。但是请注意，array_flip只有当数组的值都是字符串或所有整数时，这才是安全的；如果您必须生成对象数组的并集，我建议使用array_merge和的版本array_diff。

回答by Oscar Jara

Use array_uniqueand array_mergetogether.

array_unique和array_merge一起使用。

回答by Marian Zburlea

From the code in the PHP: Array Operatorsdocumentation:

来自PHP: Array Operators文档中的代码：

<?php
$a = array("a" => "apple", "b" => "banana");
$b = array("a" => "pear", "b" => "strawberry", "c" => "cherry");

$c = $a + $b; // Union of $a and $b
echo "Union of $a and $b: \n";
var_dump($c);

$c = $b + $a; // Union of $b and $a
echo "Union of $b and $a: \n";
var_dump($c);
?>

When executed, this script will print the following:

执行时，此脚本将打印以下内容：

Union of $a and $b:
array(3) {
  ["a"]=>
  string(5) "apple"
  ["b"]=>
  string(6) "banana"
  ["c"]=>
  string(6) "cherry"
}
Union of $b and $a:
array(3) {
  ["a"]=>
  string(4) "pear"
  ["b"]=>
  string(10) "strawberry"
  ["c"]=>
  string(6) "cherry"
}

回答by RJ Anoop

use "+" operator to do so. See the link Array Operators

使用“+”运算符来做到这一点。请参阅链接数组运算符

回答by ackuser

$result = array_merge_recursive($first, $second);

can be useful when you have arrays with arrays inside.

当您有包含数组的数组时，这会很有用。

回答by Clemens Tolboom

The OP did not specify whether the union is by valueor by keyand PHP has array_mergefor merging values and +for merging the keys. The results depends on whether the array is indexed or keyed andwhich array comes first.

OP 没有指定联合是按值还是按键，PHP 具有array_merge合并值和+合并键的功能。结果取决于数组是索引还是键控以及哪个数组先出现。

$a = ['a', 'b'];
$b = ['b', 'c'];

$c = ['a' => 'A',  'b' => 'B'];
??$d = ['a' => 'AA', 'c' => 'C'];

Indexed array

索引数组

See array_merge

看 array_merge

By value using array_merge

按值使用 array_merge

??array_merge($a, $b); // [?0 => 'a', 1 => 'b', 2 => 'b', 3 => 'c']
??array_merge($b, $a); // ?[0 => 'b', 1 => 'c', 2 => 'a', 3 => 'b']

merge by key using +operator

使用+运算符按键合并

See +operator

见+运营商

??$a + $b; ?// [0 => 'a', 1 => 'b']
$b + $a; // [0 => 'b', 1 => 'c']

Keyed array

键控数组

By value using array_merge

按值使用 array_merge

?array_merge($c, $d); // ?['a' => 'AA', 'b' => 'B', 'c' => 'C']
array_merge($d, $c); // ['a' => 'A',  'c' => 'C', 'b' => 'B']

merge by key using +operator

使用+运算符按键合并

$c + $d; // [?'a' => 'A',  'b' => 'B', 'c' => 'C']
??$d + $c; // ?['a' => 'AA', 'c' => 'C', 'b' => 'B']

回答by Paul

The +operator:

该+操作：

$x[0] = 4;
$x[1] = 1;

$y[0] = 9;
$y[2] = 5;

$u = $y + $x;

// Results in:
$u[0] === 9;
$u[1] === 1;
$u[2] === 5;

Note that $x + $y!= $y + $x

请注意$x + $y！=$y + $x

回答by Altaf Hussain

Just use $array1 + $array2It will result union of both array.

只需使用 $array1 + $array2它将导致两个数组的并集。