geojsonio tutorial
for v0.1.8
geojsonio converts geographic data to geojson and topojson formats. Nothing else. We hope to do this one job very well, and handle all reasonable use cases.
Functions in this package are organized first around what you’re working with or want to get, geojson or topojson, then convert to or read from various formats:
geojson_list() - convert to geojson as R list formatgeojson_json() - convert to geojson as jsongeojson_sp() - convert output of geojson_list() or geojson_json() to spatial objectsgeojson_read()/topojson_read() - read a geojson/topojson file from file path or URLgeojson_write() - write a geojson file locally (no write topojson yet)
Each of the above functions have methods for various objects/classes, including numeric, data.frame, list, SpatialPolygons, SpatialLines, SpatialPoints, etc.
Additional functions:
map_gist() - push up a geojson or topojson file as a GitHub gist (renders as an interactive map) - See the maps with geojsonio vignette.map_leaf() - create a local interactive map with the leaflet package - See the maps with geojsonio vignette.
## Installation
Install rgdal - in case you can't get it installed from binary , here's what works on a Mac (change to the version of `rgdal` and `GDAL` you have).
```r
install.packages("http://cran.r-project.org/src/contrib/rgdal_0.9-1.tar.gz", repos = NULL, type="source", configure.args = "--with-gdal-config=/Library/Frameworks/GDAL.framework/Versions/1.11/unix/bin/gdal-config --with-proj-include=/Library/Frameworks/PROJ.framework/unix/include --with-proj-lib=/Library/Frameworks/PROJ.framework/unix/lib")
```
__Install geojsonio__
Stable version from CRAN
```r
install.packages("geojsonio")
```
Development version from GitHub
```r
if (!require("devtools")) install.packages("devtools")
devtools::install_github("ropensci/geojsonio")
```
```r
library("geojsonio")
```
## GeoJSON
### Convert various formats to geojson
From a `numeric` vector of length 2
as _json_
```r
geojson_json(c(32.45, -99.74))
#> {"type":"FeatureCollection","features":[{"type":"Feature","geometry":{"type":"Point","coordinates":[32.45,-99.74]},"properties":{}}]}
```
as a __list__
```r
geojson_list(c(32.45, -99.74))
#> $type
#> [1] "FeatureCollection"
#>
#> $features
#> $features[[1]]
#> $features[[1]]$type
#> [1] "Feature"
#>
#> $features[[1]]$geometry
#> $features[[1]]$geometry$type
...
```
From a `data.frame`
as __json__
```r
library('maps')
data(us.cities)
geojson_json(us.cities[1:2, ], lat = 'lat', lon = 'long')
#> {"type":"FeatureCollection","features":[{"type":"Feature","geometry":{"type":"Point","coordinates":[-99.74,32.45]},"properties":{"name":"Abilene TX","country.etc":"TX","pop":"113888","capital":"0"}},{"type":"Feature","geometry":{"type":"Point","coordinates":[-81.52,41.08]},"properties":{"name":"Akron OH","country.etc":"OH","pop":"206634","capital":"0"}}]}
```
as a __list__
```r
geojson_list(us.cities[1:2, ], lat = 'lat', lon = 'long')
#> $type
#> [1] "FeatureCollection"
#>
#> $features
#> $features[[1]]
#> $features[[1]]$type
#> [1] "Feature"
#>
#> $features[[1]]$geometry
#> $features[[1]]$geometry$type
...
```
From `SpatialPolygons` class
```r
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)
```
to __json__
```r
geojson_json(sp_poly)
#> {"type":"FeatureCollection","features":[{"type":"Feature","id":1,"properties":{"dummy":0},"geometry":{"type":"Polygon","coordinates":[[[-100,40],[-90,50],[-85,45],[-100,40]]]}},{"type":"Feature","id":2,"properties":{"dummy":0},"geometry":{"type":"Polygon","coordinates":[[[-90,30],[-80,40],[-75,35],[-90,30]]]}}]}
```
to a __list__
```r
geojson_list(sp_poly)
#> $type
#> [1] "FeatureCollection"
#>
#> $features
#> $features[[1]]
#> $features[[1]]$type
#> [1] "Feature"
#>
#> $features[[1]]$id
#> [1] 1
...
```
From `SpatialPoints` class
```r
x <- c(1, 2, 3, 4, 5)
y <- c(3, 2, 5, 1, 4)
s <- SpatialPoints(cbind(x, y))
```
to __json__
```r
geojson_json(s)
#> {"type":"FeatureCollection","features":[{"type":"Feature","id":1,"properties":{"dat":1},"geometry":{"type":"Point","coordinates":[1,3]}},{"type":"Feature","id":2,"properties":{"dat":2},"geometry":{"type":"Point","coordinates":[2,2]}},{"type":"Feature","id":3,"properties":{"dat":3},"geometry":{"type":"Point","coordinates":[3,5]}},{"type":"Feature","id":4,"properties":{"dat":4},"geometry":{"type":"Point","coordinates":[4,1]}},{"type":"Feature","id":5,"properties":{"dat":5},"geometry":{"type":"Point","coordinates":[5,4]}}]}
```
to a __list__
```r
geojson_list(s)
#> $type
#> [1] "FeatureCollection"
#>
#> $features
#> $features[[1]]
#> $features[[1]]$type
#> [1] "Feature"
#>
#> $features[[1]]$id
#> [1] 1
...
```
### Write geojson
```r
library('maps')
data(us.cities)
geojson_write(us.cities[1:2, ], lat = 'lat', lon = 'long')
#>
#> Path: myfile.geojson
#> From class: data.frame
```
### Read geojson
```r
library("sp")
file <- system.file("examples", "california.geojson", package = "geojsonio")
out <- geojson_read(file, what = "sp")
plot(out)
```
## Topojson
In the current version of this package you can read topojson. Writing topojson was in this package, but is gone for now - will come back later as in interface to [topojson](https://github.com/mbostock/topojson) via [V8](https://github.com/jeroenooms/V8).
Read from a file
```r
file <- system.file("examples", "us_states.topojson", package = "geojsonio")
out <- topojson_read(file, verbose = FALSE)
summary(out)
#> Object of class SpatialPolygonsDataFrame
#> Coordinates:
#> min max
#> x -171.79111 -66.96466
#> y 18.91619 71.35776
#> Is projected: NA
#> proj4string : [NA]
#> Data attributes:
#> id name
#> Alabama : 1 NA's:51
#> Alaska : 1
#> Arizona : 1
#> Arkansas : 1
#> California: 1
#> Colorado : 1
#> (Other) :45
```
Read from a URL
```r
url <- "https://raw.githubusercontent.com/shawnbot/d3-cartogram/master/data/us-states.topojson"
out <- topojson_read(url, verbose = FALSE)
```
Or use `as.location()` first
```r
(loc <- as.location(file))
#>
#> Type: file
#> Location: /Library/Frameworks/R.framework/Versions/3.2/Resources/library/geojsonio/examples/us_states.topojson
out <- topojson_read(loc, verbose = FALSE)
```
## Citing
> Scott Chamberlain and Andy Teucher (2016). geojsonio: Convert Data from and to 'geoJSON' or 'topoJSON'. R package version 0.1.8. https://cran.rstudio.com/package=geojsonio
## License and bugs
* License: [MIT](http://opensource.org/licenses/MIT)
* Report bugs at [our GitHub repo for geojsonio](https://github.com/ropensci/geojsonio/issues?state=open)
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