nlme (version 3.1-1)

nlsList: List of nls Objects with a Common Model

Description

Data is partitioned according to the levels of the grouping factor defined in model and individual nls fits are obtained for each data partition, using the model defined in model.

Usage

nlsList(model, data, start, control, level, na.action, pool)

Arguments

model

either a nonlinear model formula, with the response on the left of a ~ operator and an expression involving parameters, covariates, and a grouping factor separated by the | operator on the right, or a selfStart<

data

a data frame in which to interpret the variables named in model.

start

an optional named list with initial values for the parameters to be estimated in model. It is passed as the start argument to each nls call and is required when the nonlinear function in model

control

a list of control values passed as the control argument to nls. Defaults to an empty list.

level

an optional integer specifying the level of grouping to be used when multiple nested levels of grouping are present.

na.action

a function that indicates what should happen when the data contain NAs. The default action (na.fail) causes nlsList to print an error message and terminate if there are any incomplete observations.

pool

an optional logical value that is preserved as an attribute of the returned value. This will be used as the default for pool in calculations of standard deviations or standard errors for summaries.

Value

• a list of nls objects with as many components as the number of groups defined by the grouping factor. Generic functions such as coef, fixed.effects, lme, pairs, plot, predict, random.effects, summary, and update have methods that can be applied to an nlsList object.

See Also

nls, nlme.nlsList.

Examples

library(nlme)
data(CO2)
fm1 <- nlsList(uptake ~ SSasympOff(conc, Asym, lrc, c0),
   data = CO2, start = c(Asym = 30, lrc = -4.5, c0 = 52))
fm1