Convert many input types with spatial data to TopoJSON as a JSON string
Convert many input types with spatial data to TopoJSON as a JSON string
topojson_json( input, lat =NULL, lon =NULL, group =NULL, geometry ="point", type ="FeatureCollection", convert_wgs84 =FALSE, crs =NULL, object_name ="foo", quantization =0,...)
Arguments
input: Input list, data.frame, spatial class, or sf class. Inputs can also be dplyr tbl_df class since it inherits from data.frame.
lat: (character) Latitude name. The default is NULL, and we attempt to guess.
lon: (character) Longitude name. The default is NULL, and we attempt to guess.
group: (character) A grouping variable to perform grouping for polygons - doesn't apply for points
geometry: (character) One of point (Default) or polygon.
type: (character) The type of collection. One of 'auto' (default for 'sf' objects), 'FeatureCollection' (default for everything else), or 'GeometryCollection'. "skip" skips the coercion with package geojson
functions; skipping can save significant run time on larger geojson objects. Spatial objects can only accept "FeatureCollection" or "skip". "skip" is not available as an option for numeric, list, and data.frame classes
convert_wgs84: Should the input be converted to the standard CRS system for GeoJSON (https://tools.ietf.org/html/rfc7946) (geographic coordinate reference system, using the WGS84 datum, with longitude and latitude units of decimal degrees; EPSG: 4326). Default is FALSE though this may change in a future package version. This will only work for sf or Spatial
objects with a CRS already defined. If one is not defined but you know what it is, you may define it in the crs argument below.
crs: The CRS of the input if it is not already defined. This can be an epsg code as a four or five digit integer or a valid proj4 string. This argument will be ignored if convert_wgs84 is FALSE or the object already has a CRS.
object_name: (character) name to give to the TopoJSON object created. Default: "foo"
...: args passed down to geojson_json(); see geojson_json() for help on what's supported here
Returns
An object of class geo_json (and json)
Details
The type parameter is automatically converted to type="auto" if a sf, sfc, or sfg class is passed to input
Examples
## Not run:# From a numeric vector of length 2, making a point typetopojson_json(c(-99.74,32.45), pretty =TRUE)topojson_json(c(-99.74,32.45), type ="GeometryCollection")## polygon type### this requires numeric class input, so inputting a list will dispatch on the list methodpoly <- c( c(-114.345703125,39.436192999314095), c(-114.345703125,43.45291889355468), c(-106.61132812499999,43.45291889355468), c(-106.61132812499999,39.436192999314095), c(-114.345703125,39.436192999314095))topojson_json(poly, geometry ="polygon", pretty =TRUE)# Lists## From a list of numeric vectors to a polygonvecs <- list(c(100.0,0.0), c(101.0,0.0), c(101.0,1.0), c(100.0,1.0), c(100.0,0.0))topojson_json(vecs, geometry ="polygon", pretty =TRUE)## from a named listmylist <- list( list(latitude =30, longitude =120, marker ="red"), list(latitude =30, longitude =130, marker ="blue"))topojson_json(mylist, lat ="latitude", lon ="longitude")# From a data.frame to pointstopojson_json(us_cities[1:2,], lat ="lat", lon ="long", pretty =TRUE)topojson_json(us_cities[1:2,], lat ="lat", lon ="long", type ="GeometryCollection", pretty =TRUE)# from data.frame to polygonshead(states)## make list for input to e.g., rMapstopojson_json(states[1:351,], lat ="lat", lon ="long", geometry ="polygon", group ="group")# from a geo_lista <- geojson_list(us_cities[1:2,], lat ="lat", lon ="long")topojson_json(a)# sp classes## From SpatialPolygons classlibrary("sp")poly1 <- Polygons(list(Polygon(cbind( c(-100,-90,-85,-100), c(40,50,45,40)))),"1")poly2 <- Polygons(list(Polygon(cbind( c(-90,-80,-75,-90), c(30,40,35,30)))),"2")sp_poly <- SpatialPolygons(list(poly1, poly2),1:2)topojson_json(sp_poly)topojson_json(sp_poly, pretty =TRUE)## data.frame to geojsongeojson_write(us_cities[1:2,], lat ="lat", lon ="long")%>% as.json()# From SpatialPoints classx <- c(1,2,3,4,5)y <- c(3,2,5,1,4)s <- SpatialPoints(cbind(x, y))topojson_json(s)## From SpatialPointsDataFrame classs <- SpatialPointsDataFrame(cbind(x, y), mtcars[1:5,])topojson_json(s)## From SpatialLines classlibrary("sp")c1 <- cbind(c(1,2,3), c(3,2,2))c2 <- cbind(c1[,1]+.05, c1[,2]+.05)c3 <- cbind(c(1,2,3), c(1,1.5,1))L1 <- Line(c1)L2 <- Line(c2)L3 <- Line(c3)Ls1 <- Lines(list(L1), ID ="a")Ls2 <- Lines(list(L2, L3), ID ="b")sl1 <- SpatialLines(list(Ls1))sl12 <- SpatialLines(list(Ls1, Ls2))topojson_json(sl1)topojson_json(sl12)## From SpatialLinesDataFrame classdat <- data.frame( X = c("Blue","Green"), Y = c("Train","Plane"), Z = c("Road","River"), row.names = c("a","b"))sldf <- SpatialLinesDataFrame(sl12, dat)topojson_json(sldf)topojson_json(sldf, pretty =TRUE)## From SpatialGridx <- GridTopology(c(0,0), c(1,1), c(5,5))y <- SpatialGrid(x)topojson_json(y)## From SpatialGridDataFramesgdim <- c(3,4)sg <- SpatialGrid(GridTopology(rep(0,2), rep(10,2), sgdim))sgdf <- SpatialGridDataFrame(sg, data.frame(val =1:12))topojson_json(sgdf)# From SpatialPixelslibrary("sp")pixels <- suppressWarnings(SpatialPixels(SpatialPoints(us_cities[c("long","lat")])))summary(pixels)topojson_json(pixels)# From SpatialPixelsDataFramelibrary("sp")pixelsdf <- suppressWarnings( SpatialPixelsDataFrame(points = canada_cities[c("long","lat")], data = canada_cities))topojson_json(pixelsdf)# From sf classes:if(require(sf)){## sfg (a single simple features geometry) p1 <- rbind(c(0,0), c(1,0), c(3,2), c(2,4), c(1,4), c(0,0)) poly <- rbind(c(1,1), c(1,2), c(2,2), c(1,1)) poly_sfg <- st_polygon(list(p1)) topojson_json(poly_sfg)## sfc (a collection of geometries) p1 <- rbind(c(0,0), c(1,0), c(3,2), c(2,4), c(1,4), c(0,0)) p2 <- rbind(c(5,5), c(5,6), c(4,5), c(5,5)) poly_sfc <- st_sfc(st_polygon(list(p1)), st_polygon(list(p2))) topojson_json(poly_sfc)## sf (collection of geometries with attributes) p1 <- rbind(c(0,0), c(1,0), c(3,2), c(2,4), c(1,4), c(0,0)) p2 <- rbind(c(5,5), c(5,6), c(4,5), c(5,5)) poly_sfc <- st_sfc(st_polygon(list(p1)), st_polygon(list(p2))) poly_sf <- st_sf(foo = c("a","b"), bar =1:2, poly_sfc) topojson_json(poly_sf)}## Pretty print a json stringtopojson_json(c(-99.74,32.45))topojson_json(c(-99.74,32.45))%>% pretty()## End(Not run)