Get data frame with polygons id and Centroid (lat long) information from shapefile

怎甘沉沦 提交于 2019-12-05 04:20:31
library(rgdal)
library(rgeos)

# download w/o wasting bandwidth
URL <- "ftp://dnrftp.dnr.ne.gov/pub/data/state/Legislative2010UTM.zip"
fil <- basename(URL)
if (!file.exists(fil)) download.file(URL, fil)

# unzip & get list of files
fils <- unzip(fil)

# find the shapefile in it
shp <- grep("shp$", fils, value=TRUE)

# get the first layer from it
lay <- ogrListLayers(shp)[1]

# read in the shapefile
leg <- readOGR(shp, lay)

# get the centroids and then convert them to a SpatialPointsDataFrame
leg_centers <- SpatialPointsDataFrame(gCentroid(leg, byid=TRUE), 
                                      leg@data, match.ID=FALSE)

It's just a matter of preserving the @data slot from the original shapefile then making a SpatialPointsDataFrame from the new centroids.

Then you can create a data frame from it or use it in plots or other Spatial… operations directly.

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