geoaxe introduction

geoaxe helps you split geospatial objects into pieces. It includes support for spatial object inputs (e.g., SpatialPolygons), Well-Known Text (WKT), and GeoJSON (character and list).

But, Why?

The use case we have at rOpenSci is that often web APIs accept WKT, but the WKT string can only be so long. If the string is longer than allowed by a web API, then one option is to split up the WKT string into many, and do a request on each one of those.

Surely there are other use cases for splitting up geospatial objects :)

Installation

Install from CRAN

install.packages("geoaxe")

Or install the development version from GitHub

devtools::install_github("ropenscilabs/geoaxe")

Load geoaxe (as well as sp and rgeos)

library("geoaxe")
library("sp")
library("rgeos")

Spatial Polygons and friends input

Works for SpatialPolygons and SpatialPolygonsDataFrame for now, may include other classes later

wkt <- "POLYGON((-180 -20, -140 55, 10 0, -140 -60, -180 -20))"
poly <- rgeos::readWKT(wkt)
polys <- chop(x = poly)

Plot original polygon

plot(poly, lwd = 6)

Add chopped up polygon bits

plot(polys, add = TRUE)

Well-Known Text input

wkt <- "POLYGON((-180 -20, -140 55, 10 0, -140 -60, -180 -20))"
plot(chop(wkt))

Manipulate number of cells

plots go left to right, then down, and repeat

layout(matrix(c(1,2,3,4), 2, 2, byrow = TRUE))
par(mar = c(1, 0, 1, 0))
plot(chop(wkt, n = 10))
plot(chop(wkt, n = 15))
plot(chop(wkt, n = 20))
plot(chop(wkt, n = 50))

Manipulate cell size

plots go left to right, then down, and repeat

layout(matrix(1:8, 4, 2, byrow = TRUE))
par(mar = c(1, 0, 1, 0))
plot(chop(wkt, size = 2))
plot(chop(wkt, size = 4))
plot(chop(wkt, size = 8))
plot(chop(wkt, size = 15))
plot(chop(wkt, size = 25))
plot(chop(wkt, size = 50))
plot(chop(wkt, size = 100))
plot(chop(wkt, size = 200))