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\name{mkinfit}
\alias{mkinfit}
\title{
Fit a kinetic model to data with one or more state variables.
}
\description{
This function uses the Flexible Modelling Environment package
\code{\link{FME}} to create a function calculating the model cost, which is
then minimised, using the specified initial or fixed parameters and starting
values.
}
\usage{
mkinfit(mkinmod, observed,
parms.ini = rep(0.1, length(mkinmod$parms)),
state.ini = c(100, rep(0, length(mkinmod$diffs) - 1)),
lower = 0, upper = Inf,
fixed_parms = NULL, fixed_initials = names(mkinmod$diffs)[-1],
eigen = FALSE,
plot = FALSE, quiet = FALSE, err = NULL, weight = "none",
scaleVar = FALSE,
atol = 1e-6, ...)
}
\arguments{
\item{mkinmod}{
A list of class \code{\link{mkinmod}}, containing the kinetic model to be fitted to the data.
}
\item{observed}{
The observed data. It has to be in the long format as described in
\code{\link{modFit}}, i.e. the first column must contain the name of the
observed variable for each data point. The second column must contain the
times of observation, named "time". The third column must be named "value"
and contain the observed values. Optionally, a further column can contain
weights for each data point. If it is not named "err", its name must be
passed as a further argument named \code{err} which is then passed on to
\code{\link{modFit}}.
}
\item{parms.ini}{
A named vector if initial values for the parameters, including parameters to
be optimised and potentially also fixed parameters as indicated by \code{fixed_parms}.
The default is to set the initial values to 0.1. The setting of the initial values for
the parameters has a strong impart on performance and it lies in the responsibilty of the
user to set sensible initial values.
}
\item{state.ini}{
A named vector of initial values for the state variables of the model. In case the
observed variables are represented by more than one model variable, the names will
differ from the names of the observed variables (see \code{map} component of
\code{\link{mkinmod}}). The default is to set the initial value of the first model
variable to 100 and all others to 0.
}
\item{lower}{
Lower bounds for the parameters, passed to \code{\link{modFit}}. Defaults to 0 because
negative values to not make sense for the models currently created by \code{\link{mkinmod}}.
}
\item{upper}{
Upper bounds for the parameters, passed to \code{\link{modFit}}. Defaults to \code{Inf}
except for formation fraction parameters. Setting non-infinite upper bounds has a strong
impact on performance, and using a method like "L-BFGS-B" (by specifying an additional
\code{method} argument) is recommended.
}
\item{fixed_parms}{
The names of parameters that should not be optimised but rather kept at the values
specified in \code{parms.ini}.
}
\item{fixed_initials}{
The names of model variables for which the initial state at time 0 should be excluded
from the optimisation. Defaults to all state variables except for the first one.
}
\item{eigen}{
Should the solution of the system of differential equations be based on the
spectral decomposition of the coefficient matrix in cases that this is
possible? Be aware that the results may differ from the results returned using
the ode solver.
}
\item{plot}{
Should the observed values and the numerical solutions be plotted at each stage
of the optimisation?
}
\item{quiet}{
Suppress printing out the current model cost after each improvement?
}
\item{err }{either \code{NULL}, or the name of the column with the
\emph{error} estimates, used to weigh the residuals (see details of
\code{\link{modCost}}); if \code{NULL}, then the residuals are not weighed.
}
\item{weight}{only if \code{err}=\code{NULL}: how to weigh the
residuals, one of "none", "std", "mean", see details of \code{\link{modCost}}.
}
\item{scaleVar}{
Will be passed to \code{\link{modCost}}. Default is not to scale Variables according
to the number of observations.
}
\item{atol}{
Absolute error tolerance, passed to \code{\link{ode}}. Default is 1e-6 as in
\code{\link{lsoda}}.
}
\item{\dots}{
Further arguments that will be passed to \code{\link{modFit}}.
}
}
\value{
A list with "mkinfit" and "modFit" in the class attribute.
A summary can be obtained by \code{\link{summary.mkinfit}}.
}
\author{
Johannes Ranke <jranke@{harlan.com,uni-bremen.de}>
}
\examples{
# One parent compound, one metabolite, both single first order.
SFO_SFO <- mkinmod(
parent = list(type = "SFO", to = "m1", sink = TRUE),
m1 = list(type = "SFO"))
# Fit the model to the FOCUS example dataset D using defaults
fit <- mkinfit(SFO_SFO, FOCUS_2006_D)
str(fit)
summary(fit)
}
\keyword{ models }
\keyword{ optimize }
|
