Convert many input types with spatial data to TopoJSON as a list
topojson_list(
input,
lat = NULL,
lon = NULL,
group = NULL,
geometry = "point",
type = "FeatureCollection",
convert_wgs84 = FALSE,
crs = NULL,
object_name = "foo",
quantization = 0,
...
)a list with TopoJSON
Input list, data.frame, spatial class, or sf class. Inputs can
also be dplyr tbl_df class since it inherits from data.frame
(character) Latitude name. The default is NULL, and we
attempt to guess.
(character) Longitude name. The default is NULL, and we
attempt to guess.
(character) A grouping variable to perform grouping for polygons - doesn't apply for points
(character) One of point (Default) or polygon.
(character) The type of collection. One of FeatureCollection (default) or GeometryCollection.
Should the input be converted to the
standard CRS 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.
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.
(character) name to give to the TopoJSON object created. Default: "foo"
(numeric) quantization parameter, use this to
quantize geometry prior to computing topology. Typical values are powers of
ten (1e4, 1e5, ...), default is 0 to not perform quantization.
For more information about quantization, see this by Mike Bostock
https://stackoverflow.com/questions/18900022/topojson-quantization-vs-simplification/18921214#18921214
args passed down through topojson_json() to geojson_json();
see geojson_json() for help on what's supported here
Internally, we call topojson_json(), then use
an internal function to convert that JSON output to a list
The type parameter is automatically converted to
type="auto" if a sf, sfc, or sfg class is passed to input
if (FALSE) {
# From a numeric vector of length 2 to a point
vec <- c(-99.74, 32.45)
topojson_list(vec)
# Lists
## From a list
mylist <- list(
list(latitude = 30, longitude = 120, marker = "red"),
list(latitude = 30, longitude = 130, marker = "blue")
)
topojson_list(mylist)
## From a list of numeric vectors to a polygon
vecs <- 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_list(vecs, geometry = "polygon")
# from data.frame to points
(res <- topojson_list(us_cities[1:2, ], lat = "lat", lon = "long"))
as.json(res)
## guess lat/long columns
topojson_list(us_cities[1:2, ])
topojson_list(states[1:3, ])
topojson_list(states[1:351, ], geometry = "polygon", group = "group")
topojson_list(canada_cities[1:30, ])
# from data.frame to polygons
head(states)
topojson_list(states[1:351, ], lat = "lat", lon = "long", geometry = "polygon", group = "group")
# From SpatialPolygons class
library("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_list(sp_poly)
# From SpatialPolygonsDataFrame class
sp_polydf <- as(sp_poly, "SpatialPolygonsDataFrame")
topojson_list(input = sp_polydf)
# From SpatialPoints class
x <- c(1, 2, 3, 4, 5)
y <- c(3, 2, 5, 1, 4)
s <- SpatialPoints(cbind(x, y))
topojson_list(s)
# From SpatialPointsDataFrame class
s <- SpatialPointsDataFrame(cbind(x, y), mtcars[1:5, ])
topojson_list(s)
# From SpatialLines class
library("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_list(sl1)
topojson_list(sl12)
as.json(topojson_list(sl12))
as.json(topojson_list(sl12), pretty = TRUE)
# From SpatialLinesDataFrame class
dat <- data.frame(
X = c("Blue", "Green"),
Y = c("Train", "Plane"),
Z = c("Road", "River"), row.names = c("a", "b")
)
sldf <- SpatialLinesDataFrame(sl12, dat)
topojson_list(sldf)
as.json(topojson_list(sldf))
as.json(topojson_list(sldf), pretty = TRUE)
# From SpatialGrid
x <- GridTopology(c(0, 0), c(1, 1), c(5, 5))
y <- SpatialGrid(x)
topojson_list(y)
# From SpatialGridDataFrame
sgdim <- c(3, 4)
sg <- SpatialGrid(GridTopology(rep(0, 2), rep(10, 2), sgdim))
sgdf <- SpatialGridDataFrame(sg, data.frame(val = 1:12))
topojson_list(sgdf)
# From SpatialRings
library("rgeos")
r1 <- Ring(cbind(x = c(1, 1, 2, 2, 1), y = c(1, 2, 2, 1, 1)), ID = "1")
r2 <- Ring(cbind(x = c(1, 1, 2, 2, 1), y = c(1, 2, 2, 1, 1)), ID = "2")
r1r2 <- SpatialRings(list(r1, r2))
topojson_list(r1r2)
# From SpatialRingsDataFrame
dat <- data.frame(id = c(1, 2), value = 3:4)
r1r2df <- SpatialRingsDataFrame(r1r2, data = dat)
topojson_list(r1r2df)
# From SpatialPixels
library("sp")
pixels <- suppressWarnings(SpatialPixels(SpatialPoints(us_cities[c("long", "lat")])))
summary(pixels)
topojson_list(pixels)
# From SpatialPixelsDataFrame
library("sp")
pixelsdf <- suppressWarnings(
SpatialPixelsDataFrame(points = canada_cities[c("long", "lat")], data = canada_cities)
)
topojson_list(pixelsdf)
# From SpatialCollections
library("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")
poly <- SpatialPolygons(list(poly1, poly2), 1:2)
coordinates(us_cities) <- ~ long + lat
dat <- SpatialCollections(points = us_cities, polygons = poly)
out <- topojson_list(dat)
out[[1]]
out[[2]]
}
# 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_list(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_list(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_list(poly_sf)
}
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