打印标题并按数组值排序

Question

我有一个包含可能值的数组：

$auto_types = array(CHEVY, FORD, DODGE);

我有包含这些值的数组：

$my_cars = array(
  array("make" => "FORD", model => "Thunderbird", "year" => 1983),
  array("make" => "FORD", model => "Mustang", "year" => 1971),
  array("make" => "CHEVY", model => "Impala", "year" => 1995),
  array("make" => "DODGE", model => "Charger", "year" => 2015),
  array("make" => "CHEVY", model => "Corvette", "year" => 2011),
  array("make" => "CHEVY", model => "Camaro", "year" => 2012)
)

我想返回一个列表，该列表提供每个品牌的标题，然后按品牌对每辆车进行排序。所以输出将是：

雪佛兰：
1995 黑斑羚
2012 克尔维特
2011款科迈罗

道奇：
2015款充电器

福特：
1971 年野马
1983 雷鸟

我知道我可以运行 foreach() 循环并按品牌排序，但这里的关键是我想要每个品牌的标题，而不是为每辆车列出它。这样做的好方法？ -- 不确定是否需要第一个数组，但当时创建它似乎是个好主意。

Answer 1

首先，您需要通过 make 对数组进行排序。您可以在array_multisort() 的帮助下做到这一点。

当您遍历数组以获取列表输出时，您可以保留一个变量来存储前一辆车的品牌。然后，每当有新品牌时，只需在汽车进入前打印一个标题。

$ex_make = '';

foreach($my_cars as $car) {
    ...
    if ($car['make'] != $ex_make) {
        print_header($car['make']);
    }
    ...
    $ex_make = $car['make'];
}

您可以通过 make 将汽车分组到一个多维数组中来让您的生活更轻松。它将使您免于排序过程（以及其他答案中建议的分组循环）。如果你有更多的汽车进来，你会想要考虑使用数据库来代替。

Answer 2

您不需要第一个数组。您可以使用一个循环按品牌对汽车进行分组：

foreach ($my_cars as $car) {
    $makes[$car['make']][] = $car;
}

如果您希望品牌按字母顺序显示，那么您可以ksort($makes)。

然后遍历品牌并打印每个品牌的汽车。

foreach ($makes as $make => $cars) {
    echo "$make: ";                       // Header prints once
    foreach ($cars as $car) {
        echo "$car[model] $car[year] ";   // Multiple cars print after each header
    }
    echo '<br>';
}

Answer 3

<?php

$my_cars = array(
  array("make" => "FORD", "model" => "Thunderbird", "year" => 1983),
  array("make" => "FORD", "model" => "Mustang", "year" => 1971),
  array("make" => "CHEVY", "model" => "Impala", "year" => 1995),
  array("make" => "DODGE", "model" => "Charger", "year" => 2015),
  array("make" => "CHEVY", "model" => "Corvette", "year" => 2011),
  array("make" => "CHEVY", "model" => "Camaro", "year" => 2012)
);

// defining empty arrays for each models
$ford = [];
$chevy = [];
$dodge = [];

// loop through every car and push to the right array model
foreach($my_cars as $array) {
  if($array['make'] == "FORD") {
    array_push($ford, $array);
  } elseif($array['make'] == "CHEVY") {
    array_push($chevy, $array);
  } else {
    array_push($dodge, $array);
  }
}

// echo the result by looping inside each array model
foreach($dodge as $car) {
  echo $car['year'] . ':' . $car['model'] . '<br />';
}

echo '<br />';

foreach($ford as $car) {
  echo $car['year'] . ':' . $car['model'] . '<br />';
}

echo '<br />';

foreach($chevy as $car) {
  echo $car['year'] . ':' . $car['model'] . '<br />';
}

Answer 4

嵌套循环在这里是理想的。

    <?php
        $auto_types = array("CHEVY", "FORD", "DODGE");
        $my_cars    = array(
            array("make" => "FORD",  "model" => "Thunderbird",  "year" => 1983),
            array("make" => "FORD",  "model" => "Mustang",      "year" => 1971),
            array("make" => "CHEVY", "model" => "Impala",       "year" => 1995),
            array("make" => "DODGE", "model" => "Charger",      "year" => 2015),
            array("make" => "CHEVY", "model" => "Corvette",     "year" => 2011),
            array("make" => "CHEVY", "model" => "Camaro",       "year" => 2012)
        );

        $arr = [];
        foreach($my_cars as $my_car){
            foreach($auto_types as $auto_type){
                if($make = array_search($auto_type, $my_car)){
                    $desc   = $my_car['make'] . " " . $my_car['year'] . " " . $my_car['model'];
                    if(!array_key_exists($auto_type, $arr)){
                        $arr[$auto_type] = $desc;
                    }else{
                        $arr[$auto_type] = $arr[$auto_type] .  "    " . $my_car['year'] . " " . $my_car['model'] . "";
                    }
                }
            }
        }
        ksort($arr);

        var_dump ($arr);
        // PRODUCES::           
        array (size=3)
          'CHEVY' => string 'CHEVY 1995 Impala    2011 Corvette    2012 Camaro' (length=49)
          'DODGE' => string 'DODGE 2015 Charger' (length=18)
          'FORD' => string 'FORD 1983 Thunderbird    1971 Mustang' (length=37)

        $output = implode("<br />", $arr);
        echo $output;

        // PRODUCES::
        CHEVY 1995 Impala 2011 Corvette 2012 Camaro
        DODGE 2015 Charger
        FORD 1983 Thunderbird 1971 Mustang

有效代码

    <?php
        $arr = [];
        foreach($my_cars as $my_car){
            foreach($auto_types as $auto_type){
                if($make = array_search($auto_type, $my_car)){
                    $desc   = $my_car['make'] . " " . $my_car['year'] . " " . $my_car['model'];
                    if(!array_key_exists($auto_type, $arr)){
                        $arr[$auto_type] = $desc;
                    }else{
                        $arr[$auto_type] = $arr[$auto_type] .  "    " . $my_car['year'] . " " . $my_car['model'] . "";
                    }
                }
            }
        }
        ksort($arr);
        $output = implode("<br />", $arr);  //<== GET STRING VALUE...
        echo $output;