nlme.mmkin: Create an nlme model for an mmkin row object

In mkin: Kinetic Evaluation of Chemical Degradation Data

Create an nlme model for an mmkin row object

Description

This functions sets up a nonlinear mixed effects model for an mmkin row object. An mmkin row object is essentially a list of mkinfit objects that have been obtained by fitting the same model to a list of datasets.

Usage

## S3 method for class 'mmkin'
nlme(
  model,
  data = "auto",
  fixed = lapply(as.list(names(mean_degparms(model))), function(el) eval(parse(text =
    paste(el, 1, sep = "~")))),
  random = pdDiag(fixed),
  groups,
  start = mean_degparms(model, random = TRUE, test_log_parms = TRUE),
  correlation = NULL,
  weights = NULL,
  subset,
  method = c("ML", "REML"),
  na.action = na.fail,
  naPattern,
  control = list(),
  verbose = FALSE
)

## S3 method for class 'nlme.mmkin'
print(x, digits = max(3, getOption("digits") - 3), ...)

## S3 method for class 'nlme.mmkin'
update(object, ...)

Arguments

model	An mmkin row object.
data	Ignored, data are taken from the mmkin model
fixed	Ignored, all degradation parameters fitted in the mmkin model are used as fixed parameters
random	If not specified, no correlations between random effects are set up for the optimised degradation model parameters. This is achieved by using the nlme::pdDiag method.
groups	See the documentation of nlme
start	If not specified, mean values of the fitted degradation parameters taken from the mmkin object are used
correlation	See the documentation of nlme
weights	passed to nlme
subset	passed to nlme
method	passed to nlme
na.action	passed to nlme
naPattern	passed to nlme
control	passed to nlme
verbose	passed to nlme
x	An nlme.mmkin object to print
digits	Number of digits to use for printing
...	Update specifications passed to update.nlme
object	An nlme.mmkin object to update

Details

Note that the convergence of the nlme algorithms depends on the quality of the data. In degradation kinetics, we often only have few datasets (e.g. data for few soils) and complicated degradation models, which may make it impossible to obtain convergence with nlme.

Value

Upon success, a fitted 'nlme.mmkin' object, which is an nlme object with additional elements. It also inherits from 'mixed.mmkin'.

Note

As the object inherits from nlme::nlme, there is a wealth of methods that will automatically work on 'nlme.mmkin' objects, such as nlme::intervals(), nlme::anova.lme() and nlme::coef.lme().

See Also

nlme_function(), plot.mixed.mmkin, summary.nlme.mmkin

Examples

ds <- lapply(experimental_data_for_UBA_2019[6:10],
 function(x) subset(x$data[c("name", "time", "value")], name == "parent"))

## Not run: 
  f <- mmkin(c("SFO", "DFOP"), ds, quiet = TRUE, cores = 1)
  library(nlme)
  f_nlme_sfo <- nlme(f["SFO", ])
  f_nlme_dfop <- nlme(f["DFOP", ])
  anova(f_nlme_sfo, f_nlme_dfop)
  print(f_nlme_dfop)
  plot(f_nlme_dfop)
  endpoints(f_nlme_dfop)

  ds_2 <- lapply(experimental_data_for_UBA_2019[6:10],
   function(x) x$data[c("name", "time", "value")])
  m_sfo_sfo <- mkinmod(parent = mkinsub("SFO", "A1"),
    A1 = mkinsub("SFO"), use_of_ff = "min", quiet = TRUE)
  m_sfo_sfo_ff <- mkinmod(parent = mkinsub("SFO", "A1"),
    A1 = mkinsub("SFO"), use_of_ff = "max", quiet = TRUE)
  m_dfop_sfo <- mkinmod(parent = mkinsub("DFOP", "A1"),
    A1 = mkinsub("SFO"), quiet = TRUE)

  f_2 <- mmkin(list("SFO-SFO" = m_sfo_sfo,
   "SFO-SFO-ff" = m_sfo_sfo_ff,
   "DFOP-SFO" = m_dfop_sfo),
    ds_2, quiet = TRUE)

  f_nlme_sfo_sfo <- nlme(f_2["SFO-SFO", ])
  plot(f_nlme_sfo_sfo)

  # With formation fractions this does not coverge with defaults
  # f_nlme_sfo_sfo_ff <- nlme(f_2["SFO-SFO-ff", ])
  #plot(f_nlme_sfo_sfo_ff)

  # For the following, we need to increase pnlsMaxIter and the tolerance
  # to get convergence
  f_nlme_dfop_sfo <- nlme(f_2["DFOP-SFO", ],
    control = list(pnlsMaxIter = 120, tolerance = 5e-4))

  plot(f_nlme_dfop_sfo)

  anova(f_nlme_dfop_sfo, f_nlme_sfo_sfo)

  endpoints(f_nlme_sfo_sfo)
  endpoints(f_nlme_dfop_sfo)

  if (length(findFunction("varConstProp")) > 0) { # tc error model for nlme available
    # Attempts to fit metabolite kinetics with the tc error model are possible,
    # but need tweeking of control values and sometimes do not converge

    f_tc <- mmkin(c("SFO", "DFOP"), ds, quiet = TRUE, error_model = "tc")
    f_nlme_sfo_tc <- nlme(f_tc["SFO", ])
    f_nlme_dfop_tc <- nlme(f_tc["DFOP", ])
    AIC(f_nlme_sfo, f_nlme_sfo_tc, f_nlme_dfop, f_nlme_dfop_tc)
    print(f_nlme_dfop_tc)
  }

  f_2_obs <- update(f_2, error_model = "obs")
  f_nlme_sfo_sfo_obs <- nlme(f_2_obs["SFO-SFO", ])
  print(f_nlme_sfo_sfo_obs)
  f_nlme_dfop_sfo_obs <- nlme(f_2_obs["DFOP-SFO", ],
    control = list(pnlsMaxIter = 120, tolerance = 5e-4))

  f_2_tc <- update(f_2, error_model = "tc")
  # f_nlme_sfo_sfo_tc <- nlme(f_2_tc["SFO-SFO", ]) # No convergence with 50 iterations
  # f_nlme_dfop_sfo_tc <- nlme(f_2_tc["DFOP-SFO", ],
  #  control = list(pnlsMaxIter = 120, tolerance = 5e-4)) # Error in X[, fmap[[nm]]] <- gradnm

  anova(f_nlme_dfop_sfo, f_nlme_dfop_sfo_obs)


## End(Not run)

mkin documentation built on Oct. 14, 2023, 5:08 p.m.