Mercer and Hall wheat yield data
Mercer and Hall wheat yield data, based on version in Cressie (1993), p. 455.
The value of 4.03 was changed to 4.33 (wheat[71,]) 13 January 2014; thanks to Sandy Burden; cross-checked with http://www.css.cornell.edu/faculty/dgr2/teach/R/mhw.csv, which agrees.
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.
Cressie, N. A. C. (1993) Statistics for Spatial Data. Wiley, New York, p. 455.
Mercer, W. B. and Hall, A. D. (1911) The experimental error of field trials. Journal of Agricultural Science 4, 107-132.
## 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"))