Clip

#This script clips a large point shapefile (both within the US and in the Atlantic Ocean)
#of Hurricane points to states polygon.
#Import rgdal
library(rgdal)

#Import point Hurricane data
Hurricane <- readOGR(dsn = "data/Hurricane.shp", layer = "Hurricane")

#Import states polygon
states <- readOGR(dsn = "data\\UnitedStates.shp", layer = "UnitedStates")

#View the extents for both layers
bbox(Hurricane)
bbox(states)

#Create a new Hurricane layer and project the new layer to the polygon layer
HurricanePrj <- spTransform(Hurricane, CRSobj = CRS(proj4string(states)))

#View the new layers extent
bbox(HurricanePrj)

#Plot both points and polygons to ensure the the CRS transformation worked.
plot(states)
points(HurricanePrj)

#Create new object and set the newly projected layer to the polygon
HurricaneCL <- HurricanePrj[states, ]

#View the new layer to verify the clip worked.
plot(HurricaneCL)

#Write newly created clipped hurricane points to a shapefile.  Set the object to the name of
#file in this script, set the dsn to the folder you want to put the new shapefile, name the new
#shapefile using the layer object, and set the driver to "ESRI Shapefile."
writeOGR(obj = HurricaneCL, dsn = "tempdir", layer = "HurricaneCL", driver = "ESRI Shapefile")