在PHP

Question

如何按值过滤多维数组？我想在这里删除带有重复符号的硬币：

$input =  [
    ["name" => "Bitcoin", "symbol"=> "BTC"],
    ["name" => "Ethereum", "symbol"=> "ETH"],
    ["name" => "Bitcoin Cash", "symbol"=> "BCH"],
    ["name" => "Basic Attention Token", "symbol"=> "BAT"],
    ["name" => "BatCoin", "symbol"=> "BAT"]
]

输出为具有此类唯一硬币符号的数组。

$output = [
    ["name" => "Bitcoin", "symbol"=> "BTC"],
    ["name" => "Ethereum", "symbol"=> "ETH"],
    ["name" => "Bitcoin Cash", "symbol"=> "BCH"],
    ["name" => "Basic Attention Token", "symbol"=> "BAT"]
]

我试过

$symbols = array_map(function($coin){
    return $coin['symbol'];
}, $input);


$output = array_filter($input, function($coin) use ($symbols) {
    return in_array($coin['symbol'], $symbols);
});
return $output;

但我仍然列出了5个硬币。

Answer 1

您可以获得如下所示的独特对象

// make it json string first
$jsondata = '[{"name": "Bitcoin","symbol": "BTC"},{"name": "Ethereum","symbol": "ETH"},{"name": "Bitcoin Cash","symbol": "BCH"},{"name": "Basic Attention Token","symbol": "BAT"},{"name": "BatCoin","symbol": "BAT"}]';
// decode string to json objects which will generate like yours
$objects = json_decode($jsondata);
echo'<pre>';
// print first objects
print_r($objects);
$symbolHolder=[];
foreach ($objects as $key => $object) {
    // eliminate object from array which is identical symbol to others
    if(in_array($object->symbol, $symbolHolder))
    {
        array_splice($objects, $key,1);
    }
    array_push($symbolHolder, $object->symbol);

}
// now printing unique array of object
print_r($objects);

Answer 2

想出来

    $unique_dict = [];
    foreach($input as $obj) {
        $symbol = $obj['symbol'];
        $unique_dict[$symbol] = $obj;
    }
    $unique_array = array_values($unique_dict);

Answer 3

您可以使用数组函数执行此任务。

array_column - 返回数组的单个列中的值，由列键标识。

array_unique - 获取一个输入数组并返回一个没有重复值的新数组。

array_intersect_key - 返回一个数组，其中包含array1的所有条目，其中包含所有参数中都存在的键。

示例：

<?php
$json = '[
    {"name": "Bitcoin", "symbol": "BTC"},
    {"name": "Ethereum", "symbol": "ETH"},
    {"name": "Bitcoin Cash", "symbol": "BCH"},
    {"name": "Basic Attention Token", "symbol": "BAT"},
    {"name": "BatCoin", "symbol": "BAT"}
]';

$array = json_decode($json, true);
echo json_encode(
    array_intersect_key(
        $array,
        array_unique(array_column($array, 'symbol'))
    )
);