PHP解析GeoJSON文件并按分类输出指定格式坐标

需求说明 #

我有一个GeoJSON文件，需要用PHP脚本根据properties中的标签（HIGH、MDT、ENH、SLGT、MRGL、TSTM）解析并拆分文件，每个分类下输出坐标（格式为“正数， 负数”），每行一个坐标，分类结束后添加End:并换行，直到所有分类处理完成。

目标输出示例 #

"Marginal Risk"
30.48, -80.86
30.73, -82.03
31.14, -82.82
32.74, -82.82
33.87, -83.38
34.50, -83.21
35.33, -82.23
35.64, -81.15
35.58, -80.27
34.58, -78.98
34.11, -78.18
33.84, -77.43
End:

"General Risk"
29.10, -80.01
29.31, -82.96
29.84, -83.95
29.86, -85.02
30.61, -85.80
31.55, -85.96
32.90, -85.58
34.01, -85.17
35.13, -85.23
36.42, -85.35
37.10, -85.14
38.65, -83.20
39.21, -81.77
39.27, -79.95
39.74, -78.60
40.70, -77.85
42.74, -74.88
43.22, -73.25
44.08, -72.13
45.35, -70.09
45.32, -68.87
43.88, -67.73
23.92, -82.05
24.93, -80.46
26.81, -79.58
End:

现有尝试代码 #

查看数组结构的代码 #

<?php
// Define the URL
$url = "https://www.spc.noaa.gov/products/outlook/archive/2023/day1otlk_20230331_1630_cat.lyr.geojson";
// Use cURL to fetch the data
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);

// Check if the request was successful
if ($response === false) {
    echo "Failed to retrieve data: " . curl_error($ch);
} else {
    // Close the cURL handle
    curl_close($ch);

    // Parse the JSON response
    $data = json_decode($response, true);
echo '<pre>' . print_r($data, true) . '</pre>';
}

?>

初始解码代码 #

<?php
// URL of the GeoJSON file
$url = 'https://www.spc.noaa.gov/products/outlook/archive/2023/day1otlk_20230331_1630_cat.lyr.geojson';

// Get the GeoJSON data
$data = file_get_contents($url);

// Decode the JSON data
$json_data = json_decode($data, true);

// Iterate over the features in the GeoJSON data
foreach ($json_data['features'] as $feature) {
    // Get the LABEL2 value
    $label2 = $feature['properties']['LABEL2'];
    
    // Get the coordinates
    $coordinates = $feature['geometry']['coordinates'];
    
    // Convert coordinates array to string and remove brackets
    $coordinates_string = json_encode($coordinates, JSON_PRETTY_PRINT );
    
    // Print the LABEL2 value and coordinates
    echo 'LABEL2: ' . $label2 . ', coordinates: ' . $coordinates_string . "\n";
}
?>

修正后的PHP脚本 #

<?php
// GeoJSON文件URL
$url = 'https://www.spc.noaa.gov/products/outlook/archive/2023/day1otlk_20230331_1630_cat.lyr.geojson';

// 获取GeoJSON数据，优先用cURL兼容更多环境
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);

if ($response === false) {
    die("获取数据失败: " . curl_error($ch));
}
curl_close($ch);

// 解析JSON数据
$jsonData = json_decode($response, true);
if (json_last_error() !== JSON_ERROR_NONE) {
    die("JSON解析失败: " . json_last_error_msg());
}

// 定义需要处理的分类标签映射（标签到显示名称）
$categoryMap = [
    'HIGH' => 'High Risk',
    'MDT' => 'Moderate Risk',
    'ENH' => 'Enhanced Risk',
    'SLGT' => 'Slight Risk',
    'MRGL' => 'Marginal Risk',
    'TSTM' => 'Thunderstorm Risk'
];

// 先按分类整理所有坐标
$categoryData = [];
foreach ($jsonData['features'] as $feature) {
    $label = $feature['properties']['LABEL2'];
    // 只处理目标分类
    if (!isset($categoryMap[$label])) {
        continue;
    }
    
    $displayName = $categoryMap[$label];
    // 处理坐标：GeoJSON是[经度, 纬度]，需要转成"纬度, 经度"格式
    foreach ($feature['geometry']['coordinates'][0] as $coord) {
        $lat = $coord[1];
        $lon = $coord[0];
        $categoryData[$displayName][] = sprintf("%.2f, %.2f", $lat, $lon);
    }
}

// 按要求输出结果
foreach ($categoryData as $name => $coords) {
    echo "\"$name\"\n";
    foreach ($coords as $coord) {
        echo "$coord\n";
    }
    echo "End:\n\n";
}
?>

代码说明 #

• 使用cURL获取数据，兼容性比file_get_contents更好，避免因服务器配置限制无法获取数据
• 先将所有分类的坐标按显示名称归类，确保输出时同一分类的坐标集中展示
• 处理坐标格式：将GeoJSON中的[经度,纬度]转换为示例要求的纬度, 经度格式，保留两位小数
• 只处理指定的6个分类标签，自动过滤无关数据
• 严格遵循目标输出格式，每个分类结束后添加End:并换行

内容的提问来源于stack exchange，提问作者wxmikey