将数组列中的唯一值打印为逗号分隔的字符串

Question

我想将多维数组中的所有唯一Department值打印为逗号分隔的字符串，但并非所有行都有Department值。

我的数组的简化版本如下所示：

$employee = [
    ["employee_id" => 1, "Department" => "Tech"],
    ["employee_id" => 2, "Department" => "Tech"],
    ["employee_id" => 3],
    ["employee_id" => 4, "Department" => "Tech"],
    ["employee_id" => 5],
    ["employee_id" => 6, "Department" => "Crm"],
    ["employee_id" => 7],
    ["employee_id" => 8, "Department" => "Crm"],
    ["employee_id" => 9, "Department" => "Crm"],
    ["employee_id" => 10],
    ["employee_id" => 11, "Department" => "Crm"],
    ["employee_id" => 12, "Department" => "Crm"]
];

我试过：

for ($i=0; $i < count($employee); $i++) {
    print_r(array_unique($employee[$i]['Department']));
}

但是当我尝试访问不存在的部门值时会生成警告。

预期 output：

Tech,Crm

Answer 1

<?php

echo implode(",",array_unique(array_column($employee,'Department')));

使用array_column过滤Department列的值，并使用array_unique()获得Department唯一值。 现在，只需基于,它们implode() 。

Answer 2

您可以通过将第二个参数作为第三个参数重复来避免在array_column() array_unique() 。 PHP 不允许在与阵列相同的级别上重复 kay。 当遇到重复的部门时，旧值将替换为其更新的相同值。

代码：（演示）

echo implode(',', array_column($employee, 'Department', 'Department'));
// Tech,Crm