过滤二维数组的行，并通过具有类似结构的另一个数组关联第一级键

Question

我有这2个数组：

$haystack = [
    "rowid" => ["100", "200"],
    "description" => ["something", "something else"]
];
$needle = [
    "rowid" => ["200", "300", "400"],
    "description" => ["something else", "other", "other else"],
    "test" => "bye"
];

我想用

array_diff()

和

$needle

执行

$haystack

，但出现错误，因为

$needle

数组是多维的，但

test

键只有一维。

foreach ($needle as $key => $value) :
    $left[$key] = array_diff($needle[$key], $haystack[$key]);
endforeach;

警告：array_diff()：参数 #1 不是数组
警告：array_diff()：参数 #2 不是数组

我该如何解决这个问题？

我需要在

$left

数组中仅维护“rowid”和“description”值（我可以丢弃“test”值）。

$left 应该是：

Array
(
    [rowid] => Array
        (
            [0] => 300
            [1] => 400
        )

    [description] => Array
        (
            [0] => other
            [1] => other else
        )

) 

Answer 1

删除“测试”=>“再见”；来自 $needle 或以正确的方式编写它们。

//array_diff takes arguments as array.
foreach ($needle as $key => $value) :
$left[$key] = array_diff($needle[$key],$haystack[$key]);
//when $key = test $needle[$key]=bye which is not array 
//thats why you got Warning: array_diff(): Argument #1 is not an array  this warning

//again when $key=test ,$haystack[$key]=null which is not array
//thats why you got Warning: array_diff(): Argument #2 is not an array
endforeach;

Answer 2

如果要过滤的数组中的某项不是数组，或者在黑名单数组中找不到该键，则删除该行。使用两个数组时，修改输入行以包含

array_diff()

的过滤结果。 演示

$input = [
    "rowid" => ["200", "300", "400"],
    "description" => ["something else", "other", "other else"],
    "test" => "bye"
];
$blacklist = [
    "rowid" => ["100", "200"],
    "description" => ["something", "something else"]
];

$left = [];
foreach ($input as $key => $row) {
    if (is_array($row) && isset($blacklist[$key])) {
        $left[$key] = array_diff($row, $blacklist[$key]);
    }
}
var_export($left);

输出：

array (
  'rowid' => 
  array (
    1 => '300',
    2 => '400',
  ),
  'description' => 
  array (
    1 => 'other',
    2 => 'other else',
  ),
)

如果您需要索引子数组，请对过滤结果调用

array_values()

。