將數組列中的唯一值打印為逗號分隔的字符串

Question

我想將多維數組中的所有唯一Department值打印為逗號分隔的字符串，但並非所有行都有Department值。

我的數組的簡化版本如下所示：

$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"]
];

我試過：

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

但是當我嘗試訪問不存在的部門值時會生成警告。

預期 output：

Tech,Crm

Answer 1

<?php

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

使用array_column過濾Department列的值，並使用array_unique()獲得Department唯一值。 現在，只需基於,它們implode() 。

Answer 2

您可以通過將第二個參數作為第三個參數重復來避免在array_column() array_unique() 。 PHP 不允許在與陣列相同的級別上重復 kay。 當遇到重復的部門時，舊值將替換為其更新的相同值。

代碼：（演示）

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