如何移除GeoJSON重复要素，创建含唯一要素的FeatureCollection？

给定以下GeoJSON集合：

{
    "type": "FeatureCollection",
    "features": [
        {
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [
                    13.55791,
                    52.54459
                ]
            },
            "properties": {
                "title": "Sommer 2022",
                "opening_hours": null
            }
        },
        {
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [
                    13.39519,
                    52.5203
                ]
            },
            "properties": {
                "title": "Winter",
                "opening_hours": "Sa,Su,PH 11:00-17:00"
            }
        },
        {
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [
                    13.39519,
                    52.5203
                ]
            },
            "properties": {
                "title": "Winter",
                "opening_hours": "Sa,Su,PH 11:00-17:00"
            }
        }
    ]
}

如何移除重复的Feature，最终得到一个包含唯一Feature的GeoJSON集合？

解决方案 #

可以通过将Feature转换为唯一字符串标识，结合Set数据结构过滤重复项，具体实现如下：

代码示例

// 原始GeoJSON数据
const originalGeoJSON = {
    "type": "FeatureCollection",
    "features": [
        {
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [13.55791, 52.54459]
            },
            "properties": {
                "title": "Sommer 2022",
                "opening_hours": null
            }
        },
        {
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [13.39519, 52.5203]
            },
            "properties": {
                "title": "Winter",
                "opening_hours": "Sa,Su,PH 11:00-17:00"
            }
        },
        {
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [13.39519, 52.5203]
            },
            "properties": {
                "title": "Winter",
                "opening_hours": "Sa,Su,PH 11:00-17:00"
            }
        }
    ]
};

// 定义去重函数
const removeDuplicateFeatures = (geoJSON) => {
    const seen = new Set();
    // 过滤重复Feature
    const uniqueFeatures = geoJSON.features.filter(feature => {
        // 将Feature对象序列化为字符串，作为唯一标识
        const featureKey = JSON.stringify(feature);
        if (!seen.has(featureKey)) {
            seen.add(featureKey);
            return true;
        }
        return false;
    });
    // 返回包含唯一Feature的新GeoJSON集合
    return {
        ...geoJSON,
        features: uniqueFeatures
    };
};

// 执行去重并输出结果
const uniqueGeoJSON = removeDuplicateFeatures(originalGeoJSON);
console.log(JSON.stringify(uniqueGeoJSON, null, 2));

代码说明

1. 唯一标识生成：使用JSON.stringify()将每个Feature转换为字符串，完全相同的Feature会生成一致的字符串。
2. 重复过滤：利用Set的唯一性特性，记录已出现的Feature字符串标识，过滤掉重复项。
3. 返回新集合：保留原GeoJSON的其他属性，仅替换为去重后的features数组。

内容的提问来源于stack exchange，提问作者JJD