The CO2
data frame has 84 rows and 5 columns of data from an
experiment on the cold tolerance of the grass species
Echinochloa crus-galli.
CO2
An object of class
c("nfnGroupedData", "nfGroupedData", "groupedData", "data.frame")
containing the following columns:
an ordered factor with levels
Qn1
< Qn2
< Qn3
< … < Mc1
giving a unique identifier for each plant.
a factor with levels
Quebec
Mississippi
giving the origin of the plant
a factor with levels
nonchilled
chilled
a numeric vector of ambient carbon dioxide concentrations (mL/L).
a numeric vector of carbon dioxide uptake rates (\(\mu\mbox{mol}/m^2\) sec).
The \(CO_2\) uptake of six plants from Quebec and six plants from Mississippi was measured at several levels of ambient \(CO_2\) concentration. Half the plants of each type were chilled overnight before the experiment was conducted.
This dataset was originally part of package nlme
, and that has
methods (including for [
, as.data.frame
, plot
and
print
) for its grouped-data classes.
# NOT RUN { require(stats); require(graphics) # } # NOT RUN { 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) # }