如何在GTFS数据中为每趟具有多个形状的路线构建折线

Question

我正在尝试解析GTFS数据并为一条路线构建多段线形状（一组纬度和经度对）。但是在我的示例GTFS数据中，我发现行程对于一条路线具有多个形状ID。以下是GTFS数据的一段内容：

routes.txt

    route_id,agency_id,route_short_name,route_long_name,route_desc,route_type,route_url,route_color,route_text_color
    90,YRT,90,LESLIE,,3,,FDAE35,FFFFFF

trips.txt

    route_id,service_id,trip_id,trip_headsign,trip_short_name,direction_id,block_id,shape_id,wheelchair_accessible,bikes_allowed
    90,1,1286467,Richmond Green Secondary School - NB,,0,131905,59628,1,1
    90,1,1286468,Richmond Green Secondary School - NB,,0,131907,59628,1,1
    90,1,1286380,Richmond Green Secondary School - NB,,0,131906,59629,1,1
    90,1,1286469,Richmond Green Secondary School - NB,,0,131908,59628,1,1
    90,1,1286381,Richmond Green Secondary School - NB,,0,131904,59629,1,1
    90,1,1286382,Richmond Green Secondary School - NB,,0,131905,59629,1,1
    ...
    90,1,1286399,Richmond Green Secondary School - NB,,0,131960,59629,1,1
    90,1,1286400,Richmond Green Secondary School - NB,,0,131961,59629,1,1
    90,1,1286470,Richmond Green Secondary School - NB,,0,131921,59630,1,1
    90,1,1286471,Richmond Green Secondary School - NB,,0,131922,59630,1,1
    90,1,1286401,Richmond Green Secondary School - NB,,0,131962,59629,1,1
    90,1,1286402,Richmond Green Secondary School - NB,,0,131960,59629,1,2

shapes.txt

    

    shape_id,shape_pt_lat,shape_pt_lon,shape_pt_sequence,shape_dist_traveled
    59628,43.902752,-79.398992,72,7.2214
    59628,43.902585,-79.399005,73,7.2405
    59629,43.775996,-79.346326,1,0.0000
    59629,43.775987,-79.346238,2,0.0071
    ...
    59629,43.902752,-79.398992,317,15.7832
    59629,43.902585,-79.399005,318,15.8022
    59630,43.811197,-79.360774,1,0.0000
    59630,43.812373,-79.361259,2,0.1364

我希望每次旅行都可以有一个形状，或者至少形状是连续的。但是这次旅行数据让我失望：

    route_id,service_id,trip_id,trip_headsign,trip_short_name,direction_id,block_id,shape_id,wheelchair_accessible,bikes_allowed
    90,1,1286400,Richmond Green Secondary School - NB,,0,131961,59629,1,1
    90,1,1286470,Richmond Green Secondary School - NB,,0,131921,59630,1,1
    90,1,1286471,Richmond Green Secondary School - NB,,0,131922,59630,1,1
    90,1,1286401,Richmond Green Secondary School - NB,,0,131962,59629,1,1

如果您注意到＃59629形状之后，则找到＃59630。但是之后，我们再次看到＃59629。我该如何理解？是数据问题吗？

Answer 1

形状不与路线关联，形状仅与单个行程关联。一条路线包含两个或多个形状非常普遍。

实际上，由于形状明确地编码了运动方向，所以路线将始终存在至少两个形状，这些路线被分为“往返”行程对（这是简单公交路线中最常见的方法）实践）。更复杂的可能性包括具有多个分支的路线或具有短途旅行的路线。

此外，形状ID并不暗含任何排序；也就是说，59630不在59629之前还是之后都没有意义。原则上，它们是任意字符串。

总之，你的数据与外观做工精细，它只是没有明确的方式，做你想做的，一般情况下该怎么做。但是，根据你的情况的细节，有可能采取更手动方法和多个形状组合成单个相干折线。