geojsonio (version 0.8.0)

topojson_list: Convert many input types with spatial data to TopoJSON as a list

Description

Convert many input types with spatial data to TopoJSON as a list

Usage

topojson_list(input, lat = NULL, lon = NULL, group = NULL,
  geometry = "point", type = "FeatureCollection",
  convert_wgs84 = FALSE, crs = NULL, ...)

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 FeatureCollection (default) or GeometryCollection.

convert_wgs84

Should the input be converted to the standard CRS for GeoJSON (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.

...

Ignored

Value

a list with TopoJSON

Details

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

Examples

# NOT RUN {
# 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]]
# }
# NOT RUN {
# 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)
}

# }