{rjts}

The goal of {rjts} is to provide a basic {rJava} wrapper for the JTS Topology Suite <https://www.osgeo.org/projects/jts/>.

Check out the Javadoc <https://locationtech.github.io/jts/javadoc/> to see the tools that are provided via JTS.

Installation

You can install the development version of {rjts} with {remotes}

if (!requireNamespace("remotes")) install.packages("remotes")
remotes::install_github("brownag/rjts")

Requires R >= 4.0 and {rJava}.

Once the package is installed, you will need to download the required JAR files using install_jts():

library(rjts)
#> rjts (#.#.#) -- R interface to the JTS Topology Suite
#>
#>   Unable to load JTS JAR files! JARs should be downloaded to:
#>     ~/.local/share/R/rjts/
#>
#>   Run `install_jts()` to download libraries from GitHub <https://github.com/locationtech/jts/releases>.

install_jts()
#> Install complete! JAR files are now available at: ~/.local/share/R/rjts/

After running install_jts(), the JAR files will be automatically loaded when you load the package:

library(rjts)

#> rjts (#.#.#) -- R interface to the JTS Topology Suite
#> Added JTS version #.#.# to Java classpath
#>   JAR files:
#>      jts-core-#.#.#.jar
#>      JTSTestBuilder.jar

JAR files are stored in a user-specific data directory as determined by tools::R_user_dir("rjts", which = "data"), which respects R_USER_DATA_DIR, XDG_DATA_HOME, and platform defaults. This approach avoids the need to bundle JAR files in the package and keeps the git repository clean.

Example

This is an example showing how to read and write Well-Known Text (WKT) and Well-Known Binary (WKB).

You can perform various basic geometric operations by accessing Geometry class methods exposed in the read() result object. Use $ to access methods.

library(rjts)
#> rjts (0.2.0) -- R interface to the JTS Topology Suite
#>   JTS version: 1.20.0
#>   JAR files:
#>     jts-core-1.20.0.jar
#>     JTSTestBuilder.jar

wr <- WKTReader()

# read a MULTIPOLYGON from character vector
x <- wr$read("MULTIPOLYGON (((40 40, 20 45, 45 30, 40 40)),
                           ((20 35, 10 30, 10 10, 30 5, 45 20, 20 35),
                           (30 20, 20 15, 20 25, 30 20)))")
x$getGeometryType()
#> [1] "MultiPolygon"

# use the WKTWriter to return Well-Known Text
ww <- WKTWriter()
ww$writeFormatted(x$convexHull())
#> [1] "POLYGON ((30 5, 10 10, 10 30, 20 45, 40 40, 45 30, 45 20, 30 5))"

# use the WKBWriter to return Well-Known Binary
wb <- WKBWriter()
y <- wb$write(x$convexHull())

class(y)
#> [1] "raw"
y
#>   [1] 00 00 00 00 03 00 00 00 01 00 00 00 08 40 3e 00 00 00 00 00 00 40 14 00 00
#>  [26] 00 00 00 00 40 24 00 00 00 00 00 00 40 24 00 00 00 00 00 00 40 24 00 00 00
#>  [51] 00 00 00 40 3e 00 00 00 00 00 00 40 34 00 00 00 00 00 00 40 46 80 00 00 00
#>  [76] 00 00 40 44 00 00 00 00 00 00 40 44 00 00 00 00 00 00 40 46 80 00 00 00 00
#> [101] 00 40 3e 00 00 00 00 00 00 40 46 80 00 00 00 00 00 40 34 00 00 00 00 00 00
#> [126] 40 3e 00 00 00 00 00 00 40 14 00 00 00 00 00 00

# use the WKBReader to convert Well-Known Binary to a JTS Geometry object
wbr <- WKBReader()
wbr$read(y)
#> [1] "Java-Object{POLYGON ((30 5, 10 10, 10 30, 20 45, 40 40, 45 30, 45 20, 30 5))}"

# Geometry objects/results also have a toString() method that returns WKT
x$getBoundary()$toString()
#> [1] "MULTILINESTRING ((40 40, 20 45, 45 30, 40 40), (20 35, 10 30, 10 10, 30 5, 45 20, 20 35), (30 20, 20 15, 20 25, 30 20))"
x$convexHull()$toString()
#> [1] "POLYGON ((30 5, 10 10, 10 30, 20 45, 40 40, 45 30, 45 20, 30 5))"