| % File src/library/datasets/man/zCO2.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-20011 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{CO2} |
| \docType{data} |
| \alias{CO2} |
| \title{Carbon Dioxide Uptake in Grass Plants} |
| \description{ |
| The \code{CO2} data frame has 84 rows and 5 columns of data from an |
| experiment on the cold tolerance of the grass species |
| \emph{Echinochloa crus-galli}. |
| } |
| \usage{CO2} |
| \format{ |
| An object of class |
| \code{c("nfnGroupedData", "nfGroupedData", "groupedData", "data.frame")} |
| containing the following columns: |
| \describe{ |
| \item{Plant}{ |
| an ordered factor with levels |
| \code{Qn1} < \code{Qn2} < \code{Qn3} < \dots < \code{Mc1} |
| giving a unique identifier for each plant. |
| } |
| \item{Type}{ |
| a factor with levels |
| \code{Quebec} |
| \code{Mississippi} |
| giving the origin of the plant |
| } |
| \item{Treatment}{ |
| a factor with levels |
| \code{nonchilled} |
| \code{chilled} |
| } |
| \item{conc}{ |
| a numeric vector of ambient carbon dioxide concentrations (mL/L). |
| } |
| \item{uptake}{ |
| a numeric vector of carbon dioxide uptake rates |
| (\eqn{\mu\mbox{mol}/m^2}{umol/m^2} sec). |
| } |
| } |
| } |
| \details{ |
| The \eqn{CO_2}{CO2} uptake of six plants from Quebec and six plants |
| from Mississippi was measured at several levels of ambient |
| \eqn{CO_2}{CO2} concentration. Half the plants of each type were |
| chilled overnight before the experiment was conducted. |
| |
| This dataset was originally part of package \code{nlme}, and that has |
| methods (including for \code{[}, \code{as.data.frame}, \code{plot} and |
| \code{print}) for its grouped-data classes. |
| } |
| \source{ |
| Potvin, C., Lechowicz, M. J. and Tardif, S. (1990) |
| \dQuote{The statistical analysis of ecophysiological response curves |
| obtained from experiments involving repeated measures}, \emph{Ecology}, |
| \bold{71}, 1389--1400. |
| |
| Pinheiro, J. C. and Bates, D. M. (2000) |
| \emph{Mixed-effects Models in S and S-PLUS}, Springer. |
| } |
| \examples{ |
| require(stats); require(graphics) |
| \dontshow{options(show.nls.convergence=FALSE)} |
| coplot(uptake ~ conc | Plant, data = CO2, show.given = FALSE, type = "b") |
| ## fit the data for the first plant |
| fm1 <- nls(uptake ~ SSasymp(conc, Asym, lrc, c0), |
| data = CO2, subset = Plant == "Qn1") |
| summary(fm1) |
| ## fit each plant separately |
| fmlist <- list() |
| for (pp in levels(CO2$Plant)) { |
| fmlist[[pp]] <- nls(uptake ~ SSasymp(conc, Asym, lrc, c0), |
| data = CO2, subset = Plant == pp) |
| } |
| ## check the coefficients by plant |
| print(sapply(fmlist, coef), digits = 3) |
| } |
| \keyword{datasets} |