Ozone measurements {plyr}R Documentation

Monthly ozone measurements over Central America

Description

This data set is a subset of the data from the 2006 ASA Data expo challenge, http://stat-computing.org/dataexpo/2006/. The data are monthly ozone averages on a very coarse 24 by 24 grid covering Central America, from Jan 1995 to Dec 2000. The data is stored in a 3d area with the first two dimensions representing latitude and longitude, and the third representing time.

See the ozone case study in the introductory vignette (vignette("intro", "plyr")) for more details, including maps of the region.

Usage

data(ozone)

Format

A 24 x 24 x 72 numeric array

References

http://stat-computing.org/dataexpo/2006/

Examples

value <- ozone[1, 1, ]
time <- 1:72
month.abbr <- c("Jan", "Feb", "Mar", "Apr", "May", 
 "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec")
month <- factor(rep(month.abbr, length = 72), levels = month.abbr)
year <- rep(1:6, each = 12)
deseasf <- function(value) lm(value ~ month - 1)

models <- alply(ozone, 1:2, deseasf)
coefs <- laply(models, coef)
dimnames(coefs)[[3]] <- month.abbr
names(dimnames(coefs))[3] <- "month"

deseas <- laply(models, resid)
dimnames(deseas)[[3]] <- 1:72
names(dimnames(deseas))[3] <- "time"

dim(coefs)
dim(deseas)

[Package plyr version 0.1.1 Index]