geojson operations

The hardware and bandwidth for this mirror is donated by dogado GmbH, the Webhosting and Full Service-Cloud Provider. Check out our Wordpress Tutorial.
If you wish to report a bug, or if you are interested in having us mirror your free-software or open-source project, please feel free to contact us at mirror[@]dogado.de.

geojson operations

Scott Chamberlain and Jeroen Ooms

2023-07-25

inspect the object

Get the string

y[[1]]
#> [1] "{\n \"type\": \"GeometryCollection\",\n \"geometries\": [\n   {\n     \"type\": \"Point\",\n     \"coordinates\": [100.0, 0.0]\n   },\n   {\n     \"type\": \"LineString\",\n     \"coordinates\": [ [101.0, 0.0], [102.0, 1.0] ]\n   }\n  ]\n}"

Get the type

geo_type(y)
#> [1] "GeometryCollection"

Pretty print the geojson

geo_pretty(y)
#> {
#>     "type": "GeometryCollection",
#>     "geometries": [
#>         {
#>             "type": "Point",
#>             "coordinates": [
#>                 100.0,
#>                 0.0
#>             ]
#>         },
#>         {
#>             "type": "LineString",
#>             "coordinates": [
#>                 [
#>                     101.0,
#>                     0.0
#>                 ],
#>                 [
#>                     102.0,
#>                     1.0
#>                 ]
#>             ]
#>         }
#>     ]
#> }
#>

Write to disk

geo_write(y, f <- tempfile(fileext = ".geojson"))
jsonlite::fromJSON(f, FALSE)
#> $type
#> [1] "GeometryCollection"
#> 
#> $geometries
#> $geometries[[1]]
#> $geometries[[1]]$type
#> [1] "Point"
#> 
#> $geometries[[1]]$coordinates
#> $geometries[[1]]$coordinates[[1]]
#> [1] 100
#> 
#> $geometries[[1]]$coordinates[[2]]
#> [1] 0
#> 
#> 
#> 
#> $geometries[[2]]
#> $geometries[[2]]$type
#> [1] "LineString"
#> 
#> $geometries[[2]]$coordinates
#> $geometries[[2]]$coordinates[[1]]
#> $geometries[[2]]$coordinates[[1]][[1]]
#> [1] 101
#> 
#> $geometries[[2]]$coordinates[[1]][[2]]
#> [1] 0
#> 
#> 
#> $geometries[[2]]$coordinates[[2]]
#> $geometries[[2]]$coordinates[[2]][[1]]
#> [1] 102
#> 
#> $geometries[[2]]$coordinates[[2]][[2]]
#> [1] 1

properties

Add properties

x <- '{ "type": "LineString", "coordinates": [ [100.0, 0.0], [101.0, 1.0] ]}'
res <- linestring(x) %>% feature() %>% properties_add(population = 1000)
res
#> <Feature> 
#>   type:  LineString 
#>   coordinates:  [[100,0],[101,1]]

Get a property

properties_get(res, property = 'population')
#> 1000

crs

Add crs

crs <- '{
  "type": "name",
  "properties": {
     "name": "urn:ogc:def:crs:OGC:1.3:CRS84"
  }
}'
z <- x %>% feature() %>% crs_add(crs)
z
#> {
#>     "type": "Feature",
#>     "properties": {
#> 
#>     },
#>     "geometry": {
#>         "type": "LineString",
#>         "coordinates": [
#>             [
#>                 100,
#>                 0
#>             ],
#>             [
#>                 101,
#>                 1
#>             ]
#>         ]
#>     },
#>     "crs": {
#>         "type": "name",
#>         "properties": {
#>             "name": "urn:ogc:def:crs:OGC:1.3:CRS84"
#>         }
#>     }
#> }

Get crs

crs_get(z)
#> $type
#> [1] "name"
#> 
#> $properties
#> $properties$name
#> [1] "urn:ogc:def:crs:OGC:1.3:CRS84"

bbox

Add bbox - by default, if you don’t pass a bbox into bbox_add() we attempt to calculate the bbox for you. You can also pass in your own bbox.

tt <- x %>% feature() %>% bbox_add()
tt
#> {
#>     "type": "Feature",
#>     "properties": {
#> 
#>     },
#>     "geometry": {
#>         "type": "LineString",
#>         "coordinates": [
#>             [
#>                 100,
#>                 0
#>             ],
#>             [
#>                 101,
#>                 1
#>             ]
#>         ]
#>     },
#>     "bbox": [
#>         100,
#>         0,
#>         101,
#>         1
#>     ]
#> }

Get bbox

bbox_get(tt)
#> [1] 100   0 101   1

geojson in data.frame’s

It’s really easy to put geojson class objects into data.frame’s as well.

The ideal solution is to put them into tbl’s (see the tibble package)

Make a point

x <- '{ "type": "Point", "coordinates": [100.0, 0.0] }'
(pt <- point(x))
#> <Point> 
#>   coordinates:  [100,0]

Put the point into a tbl

library("tibble")
data_frame(a = 1:5, b = list(pt))
#> # A tibble: 5 × 2
#>       a b             
#>   <int> <list>        
#> 1     1 <geopoint [1]>
#> 2     2 <geopoint [1]>
#> 3     3 <geopoint [1]>
#> 4     4 <geopoint [1]>
#> 5     5 <geopoint [1]>

Another object, here a multilinestring

x <- '{ "type": "MultiLineString",
  "coordinates": [ [ [100.0, 0.0], [101.0, 1.0] ], [ [102.0, 2.0], [103.0, 3.0] ] ] }'
(mls <- multilinestring(x))
#> <MultiLineString> 
#>   no. lines:  2 
#>   no. nodes / line:  2, 2 
#>   coordinates:  [[[100,0],[101,1]],[[102,2],[103,3]]]

Put into a tbl

data_frame(a = 1:5, b = list(mls))
#> # A tibble: 5 × 2
#>       a b             
#>   <int> <list>        
#> 1     1 <gmltlnst [1]>
#> 2     2 <gmltlnst [1]>
#> 3     3 <gmltlnst [1]>
#> 4     4 <gmltlnst [1]>
#> 5     5 <gmltlnst [1]>

Put the point and multilinestring into the same tbl

(df <- data_frame(a = 1:5, b = list(pt), c = list(mls)))
#> # A tibble: 5 × 3
#>       a b              c             
#>   <int> <list>         <list>        
#> 1     1 <geopoint [1]> <gmltlnst [1]>
#> 2     2 <geopoint [1]> <gmltlnst [1]>
#> 3     3 <geopoint [1]> <gmltlnst [1]>
#> 4     4 <geopoint [1]> <gmltlnst [1]>
#> 5     5 <geopoint [1]> <gmltlnst [1]>

And you can pull the geojson back out

df$b
#> [[1]]
#> <Point> 
#>   coordinates:  [100,0] 
#> 
#> [[2]]
#> <Point> 
#>   coordinates:  [100,0] 
#> 
#> [[3]]
#> <Point> 
#>   coordinates:  [100,0] 
#> 
#> [[4]]
#> <Point> 
#>   coordinates:  [100,0] 
#> 
#> [[5]]
#> <Point> 
#>   coordinates:  [100,0]
df$b[[1]]
#> <Point> 
#>   coordinates:  [100,0]

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.
Health stats visible at Monitor.