spdep (version 0.6-9)

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)

Format

The format of the object generated by running data(wheat) is a three column data frame made available by Hongfei Li. The example section shows how to convert this to the object used in demonstrating the aple function, and is a: Formal class 'SpatialPolygonsDataFrame' [package "sp"] with 5 slots; the data slot is a data frame with 500 observations on the following 6 variables.

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

## Not run: 
# 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)
# ## End(Not run)
require(maptools)
wheat <- readShapeSpatial(system.file("etc/shapes/wheat.shp",
 package="spdep")[1])