spdep (version 0.5-74)

wheat: Mercer and Hall wheat yield data

Description

Mercer and Hall wheat yield data, based on version in Cressie (1993), p. 455.

Usage

data(wheat)

source

Cressie, N. A. C. (1993) Statistics for Spatial Data. Wiley, New York, p. 455.

References

Mercer, W. B. and Hall, A. D. (1911) The experimental error of field trials. Journal of Agricultural Science 4, 107-132.

Examples

data(wheat)
wheat$lat1 <- 69 - wheat$lat
wheat$r <- factor(wheat$lat1)
wheat$c <- factor(wheat$lon)
wheat_sp <- wheat
coordinates(wheat_sp) <- c("lon", "lat1")
wheat_spg <- wheat_sp
gridded(wheat_spg) <- TRUE
wheat_spl <- as(wheat_spg, "SpatialPolygons")
df <- as(wheat_spg, "data.frame")
row.names(df) <- sapply(slot(wheat_spl, "polygons"),
 function(x) slot(x, "ID"))
wheat <- SpatialPolygonsDataFrame(wheat_spl, data=df)
require(maptools)
wheat <- readShapeSpatial(system.file("etc/shapes/wheat.shp",
 package="spdep")[1])