如果你使用
sf
#install.packages("sf)
library(sf)
# I have downloaded the Overpass query as a GeoJSON file
route <- st_read("export.geojson")
结果是一个数据帧,每个特征表示为一行,因此您可以对其进行子集(即route[1:3,]),以仅提取您感兴趣的特征。
就这样!
让我们看看你的案子。
nrow(route)
[1] 89
有12个属性(最后一列,数字13,出现在所有
对象并保存几何数据)
names(route)
[1] "id" "X.id" "from"
[4] "name" "network" "public_transport.version"
[7] "ref" "route" "source"
[10] "to" "type" "X.relations"
[13] "geometry"
看起来像这样:
plot(route)
(只有前十个属性显示为
plot()
除非你用
max.plot = 10
)
summary(route$geometry)
MULTILINESTRING POINT epsg:4326 +proj=long...
2 87 0 0
前两行包含行,其余表示点。
head(route)
Simple feature collection with 6 features and 12 fields
geometry type: GEOMETRY
dimension: XY
bbox: xmin: 20.89744 ymin: 52.21596 xmax: 21.10796 ymax: 52.25929
epsg (SRID): 4326
proj4string: +proj=longlat +datum=WGS84 +no_defs
id X.id from
1 relation/4254149 relation/4254149 PKP Olszynka Grochowska
2 relation/4254150 relation/4254150 Stare Bemowo
3 node/32920674 node/32920674 <NA>
4 node/209094035 node/209094035 <NA>
5 node/251880529 node/251880529 <NA>
6 node/302874515 node/302874515 <NA>
name network public_transport.version ref route
1 Bus 523: PKP Olszynka Grochowska => Stare Bemowo ZTM Warszawa 2 523 bus
2 Bus 523: Stare Bemowo => PKP Olszynka Grochowska ZTM Warszawa 2 523 bus
3 <NA> <NA> <NA> <NA> <NA>
4 <NA> <NA> <NA> <NA> <NA>
5 <NA> <NA> <NA> <NA> <NA>
6 <NA> <NA> <NA> <NA> <NA>
source to type
1 RozkÅad jazdy ZTM Warszawa, trasa wygenerowana przez bot Stare Bemowo route
2 RozkÅad jazdy ZTM Warszawa, trasa wygenerowana przez bot PKP Olszynka Grochowska route
3 <NA> <NA> <NA>
4 <NA> <NA> <NA>
5 <NA> <NA> <NA>
6 <NA> <NA> <NA>
X.relations
1 <NA>
2 <NA>
3 [ { "role": "stop", "rel": 4254149, "reltags": { "from": "PKP Olszynka Grochowska", "name": "Bus 523: PKP Olszynka Grochowska => Stare Bemowo", "network": "ZTM Warszawa", "public_transport:version": "2", "ref": "523", "route": "bus", "source": "RozkÅad jazdy ZTM Warszawa, trasa wygenerowana przez bot", "to": "Stare Bemowo", "type": "route" } } ]
4 [ { "role": "stop", "rel": 4254150, "reltags": { "from": "Stare Bemowo", "name": "Bus 523: Stare Bemowo => PKP Olszynka Grochowska", "network": "ZTM Warszawa", "public_transport:version": "2", "ref": "523", "route": "bus", "source": "RozkÅad jazdy ZTM Warszawa, trasa wygenerowana przez bot", "to": "PKP Olszynka Grochowska", "type": "route" } } ]
5 [ { "role": "stop", "rel": 4254150, "reltags": { "from": "Stare Bemowo", "name": "Bus 523: Stare Bemowo => PKP Olszynka Grochowska", "network": "ZTM Warszawa", "public_transport:version": "2", "ref": "523", "route": "bus", "source": "RozkÅad jazdy ZTM Warszawa, trasa wygenerowana przez bot", "to": "PKP Olszynka Grochowska", "type": "route" } } ]
6 [ { "role": "stop", "rel": 4254150, "reltags": { "from": "Stare Bemowo", "name": "Bus 523: Stare Bemowo => PKP Olszynka Grochowska", "network": "ZTM Warszawa", "public_transport:version": "2", "ref": "523", "route": "bus", "source": "RozkÅad jazdy ZTM Warszawa, trasa wygenerowana przez bot", "to": "PKP Olszynka Grochowska", "type": "route" } } ]
geometry
1 MULTILINESTRING ((21.10695 ...
2 MULTILINESTRING ((20.89804 ...
3 POINT (21.07858 52.23575)
4 POINT (21.08457 52.24583)
5 POINT (21.07847 52.23509)
6 POINT (21.08454 52.24331)
如果您只需要,比如说,第一个特性,那么您可以相应地简化数据帧的子集:
myfeature <- route[1,]
route_lines <- route[1:2,]
plot(route_lines)
或要点:
route_stations <- route[3:89,]
plot(route_stations)
st_write(route_stations, "route_stations.geojson")
见
https://cran.r-project.org/web/packages/sf/vignettes/sf1.html
有关
平方英尺
.
