我必须用其他数组值创建一个复杂的数组。
原始数组为:
Array (
[0] => Array (
[0] => A
[1] => B
[2] => C
)
[1] => Array (
[0] => D
[1] => E
[2] => F
)
)
我正在寻找一个函数,它可以为我提供所有可能的组合值,如下所示:
Array (
[0] => Array (A, D),
[1] => Array (A, E),
[2] => Array (A, F),
[3] => Array (B, D),
[4] => Array (B, E),
[5] => Array (B, F),
[6] => Array (C, D),
[7] => Array (C, E),
[8] => Array (C, F)
)
当然,即使原始数组中的值数量不同,此算法也必须工作。
我正在 PHP 文档中寻找一个简单的函数来执行此操作,但我没有找到。
我用"多重"或"组合"等关键字在谷歌上搜索过它,但没有运气。我认为最好的方法是制作递归函数,但我找不到正确的算法。
一个简单的递归函数来计算笛卡尔积:
function cartesian(array $data)
{
function cartesian_r(array $data, array $path, &$out)
{
if (count($data) > 1) {
// recursive step
$head = array_slice($data, 0, -1);
$tail = end($data);
foreach ($tail as $item) {
cartesian_r($head, array_merge($path, [$item]), $out);
}
} else {
// unwind step
foreach ($data[0] as $item) {
$out[] = array_merge([$item], $path);
}
}
}
$out = [];
cartesian_r($data, [], $out);
return $out;
}
$out = cartesian([['A', 'B'], ['C', 'D'], ['E', 'F']]);
print_r($out);
输出
Array
(
[0] => Array
(
[0] => A
[1] => E
[2] => C
)
[1] => Array
(
[0] => B
[1] => E
[2] => C
)
[2] => Array
(
[0] => A
[1] => E
[2] => D
)
[3] => Array
(
[0] => B
[1] => E
[2] => D
)
[4] => Array
(
[0] => A
[1] => F
[2] => C
)
[5] => Array
(
[0] => B
[1] => F
[2] => C
)
[6] => Array
(
[0] => A
[1] => F
[2] => D
)
[7] => Array
(
[0] => B
[1] => F
[2] => D
)
)
只有两个
$first = array('A', 'B', 'C', 'D');
$second = array('E', 'F', 'G');
$result = array();
foreach ($first as $f) {
foreach ($second as $s) {
$result[] = array($f, $s);
}
}
var_dump($result);
这适用于尽可能多的sub_arrays,因为您不会..它不是作为原始输出排序的,但这可以通过排序函数轻松修复,如示例中所示:
$input = array(
0 => array ('A','B','C'),
1 => array ('D','E','F'),
2 => array ('X','Y','Z'),
/*...*/
);
$result = array();
foreach($input as $sub_arr){
$_result = array();
foreach($sub_arr as $val){
if($result){
foreach($result as $old){
$old[] = $val;
$_result[] = $old;
}
}else{
$_result[] = array($val);
}
}
$result = $_result;
}
array_multisort($result); //sort all layers alphabetically.
echo "<pre>";
print_r($result);
工作示例:小提琴
这是我
能想象到的最简单的动态事物:
它显示"所有可能的组合">
<?php
$origArray = array(
array(
"A",
"B",
"C"
),
array(
"D",
"E",
"F"
)
);
$endArray = array();
foreach ($origArray as $key_1 => $value_1){
foreach ($origArray as $key_2 => $value_2){
if($key_1 == $key_2){
continue;
}
foreach($value_1 as $key_1_1 => $value_1_1 ){
foreach ($value_2 as $key_2_1 => $value_2_1){
$endArray[] = array($value_1_1, $value_2_1);
}
}
}
}
echo "<pre>";
var_dump($endArray);
echo "</pre>";
如果要显示第一个子数组的所有组合,可以使用:
<?php
$origArray = array(
array(
"A",
"B",
"C"
),
array(
"D",
"E",
"F"
)
);
$endArray = array();
foreach ($origArray as $key_1 => $value_1){
foreach($origArray[0] as $key_1_1 => $value_1_1 ){
if($key_1 == 0 ){
continue;
}
foreach ($value_1 as $key_2_1 => $value_2_1){
$endArray[] = array($value_1_1, $value_2_1);
}
}
}
echo "<pre>";
var_dump($endArray);
echo "</pre>";