有人可以解释一下addGeoJSON()功能在R中是如何工作的,我无法理解文档。
?addGeoJSON => (map,geojson,layerId = NULL)
什么是geojson和layerId?
我能够使用GDAL导入我的GeoJSON: a1< - readOGR(dsn =" myData.geojson",layer =" OGRGeoJSON")
如何使用传单addGeoJSON()?
访问列以绘制x,y由于
答案 0 :(得分:6)
addGeoJSON
的第一个参数是通过调用leaflet()
创建的传单对象。例如,
url <- "https://raw.githubusercontent.com/glynnbird/usstatesgeojson/master/california.geojson"
geojson <- jsonlite::fromJSON(url)
library("leaflet")
leaflet() %>%
addTiles() %>%
setView(lng = -98.583, lat = 39.833, zoom = 3) %>%
addGeoJSON(geojson)
您可以通过readOGR
替换您创建的geojson
对象的geojson读取
使用readOGR()
library("leaflet")
library("rgdal")
url <- "https://raw.githubusercontent.com/glynnbird/usstatesgeojson/master/california.geojson"
res <- readOGR(dsn = url, layer = "OGRGeoJSON")
leaflet() %>%
addTiles() %>%
setView(lng = -98.583, lat = 39.833, zoom = 3) %>%
addPolygons(data = res)
您应该将addPolygons(data = res)
替换为addPolygons(data = res, lng = "feature.properties.long", lat = "feature.properties.lat")
应该适用于上面的例子。两者都可能会返回SpatialPolygonsDataFrame
类,您需要将其传递到data
或leaflet()
中的addPolygons()
参数。
好的,如果您正在从磁盘读取geojson文件,请使用点,例如,
geojson <- '{
"type": "FeatureCollection",
"features" :
[
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [ -123, 49 ]
},
"properties": {
"a_property": "foo",
"some_object": {
"a_property": 1,
"another_property": 2
}
}
}
]
}'
writeLines(geojson, "file.geojson")
res <- readOGR(dsn = "file.geojson", layer = "OGRGeoJSON")
leaflet() %>%
addTiles() %>%
setView(lng = -123, lat = 49, zoom = 6) %>%
addMarkers(data = res)