php中多维数组中的搜索和打印输出

Question

我正在学习PHP中的数组。我正在研究多维数组，在其中我面临一个问题。

下面是示例多维数组的说明：

Array
(
    [0] => Array
        (
            [venue] => chicago
            [course] => science
            [time] => 2pm
        )
    [1] => Array
        (
             [venue] => New York
             [course] => Robotics
             [time] => 3 p.m.
        )
    [2] => Array
        (
             [venue] => New York
             [course] => Science
             [time] => 4 p.m.
        )
    [3] => Array
        (
             [venue] => Chicago
             [course] => Robotics
             [time] => 4 p.m.
        )
)

我希望从上面的数组中打印的输出是：

Chicago
Science  2 p.m.
Robotics  4 p.m. 

New York 
Science 4 p.m.
Robotics 3 p.m. 

有人能指导我如何处理这个问题吗？

Answer 1

一种方法是首先按地点对数组进行排序。usort可以用于这一目的。

usort($events, function($a, $b) {
    return strcmp($a['venue'], $b['venue']);
});

在对数组进行排序之后，您可以迭代它，并在每次到达新地点时输出一个标头。

$previousVenue = null;
foreach ($events as $event) {

    // check if this venue is the same as the previous, output header if not
    if ($event['venue'] != $previousVenue) {
        echo "<h3>$event[venue]</h3>";
    }
    // always output course and time
    echo "$event[course] $event[time]<br>";

    // current venue becomes previous venue
    $previousVenue = $event['venue'];
}

Answer 2

为每个场馆创建一个新的数组，并分别将课程和时间作为关键和价值来存储。

// define an array
$new_array = array();
// loop the array
foreach($array as $key=>$value){
    // create an array with each venue and  course and time as key and values
    $new_array[$value['venue']][$value['course']] = $value['time'];
}

循环新数组并根据需要显示结果。

// loop the new array
foreach($new_array as $key=>$value){
    echo $key."\n";  // echo the venue
    krsort($value);  // Sort an array by key in reverse order
    foreach($value as $k=>$v){
        echo $k . ' ' . $v."\n"; // echo the course and time
    }
    echo "\n";
}

输出输出

chicago
science 2pm
robtics 4pm

newyork
science 4pm
robotics 3pm

Answer 3

您可以使用预期得到的结果如下所示。

foreach ($rows as $row) {
    echo $row['venue']."<br>";
    echo $row['firstname']."  ".$row['lastname'];
}