- IRLS is implemented

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/kinfit/pkg/mkin@109 edb9625f-4e0d-4859-8d74-9fd3b1da38cb

1 files changed, 58 insertions, 14 deletions

diff --git a/R/mkinfit.R b/R/mkinfit.R
index e7b1fb0c..b46184b7 100644
--- a/R/mkinfit.R
+++ b/R/mkinfit.R
@@ -33,6 +33,8 @@ mkinfit <- function(mkinmod, observed,
   plot = FALSE, quiet = FALSE,

   err = NULL, weight = "none", scaleVar = FALSE,

   atol = 1e-8, rtol = 1e-10, n.outtimes = 100,

+  reweight.method = NULL,

+  reweight.tol = 1e-8, reweight.max.iter = 10,

   trace_parms = FALSE,

   ...)

 {

@@ -125,7 +127,7 @@ mkinfit <- function(mkinmod, observed,
   {

     assign("calls", calls+1, inherits=TRUE) # Increase the model solution counter

 

-    # Trace parameter values if quiet is off

+    # Trace parameter values if requested

     if(trace_parms) cat(P, "\n")

 

     # Time points at which observed data are available

@@ -183,9 +185,44 @@ mkinfit <- function(mkinmod, observed,
     }

     return(mC)

   }

+

   fit <- modFit(cost, c(state.ini.optim, parms.optim), 

                 method = method.modFit, control = control.modFit, ...)

 

+  # Reiterate the fit until convergence of the variance components (IRLS)

+  # if requested by the user

+  weight.ini = weight

+  if (!is.null(err)) weight.ini = "manual"

+

+  if (!is.null(reweight.method)) {

+    if (reweight.method != "obs") stop("Only reweighting method 'obs' is implemented")

+    if(!quiet) {

+      cat("IRLS based on variance estimates for each observed variable\n")

+    }

+    if (!quiet) {

+      cat("Initial variance estimates are:\n")

+      print(signif(fit$var_ms_unweighted, 8))

+    }

+    reweight.diff = 1

+    n.iter <- 0

+    if (!is.null(err)) observed$err.ini <- observed[[err]]

+    err = "err.irls"

+    while (reweight.diff > reweight.tol & n.iter < reweight.max.iter) {

+      n.iter <- n.iter + 1

+      sigma.old <- sqrt(fit$var_ms_unweighted)

+      observed[err] <- sqrt(fit$var_ms_unweighted)[observed$name]

+      fit <- modFit(cost, fit$par, method = method.modFit,

+                    control = control.modFit, ...)

+      reweight.diff = sum((sqrt(fit$var_ms_unweighted) - sigma.old)^2)

+      if (!quiet) {

+        cat("Iteration", n.iter, "yields variance estimates:\n")

+        print(signif(fit$var_ms_unweighted, 8))

+        cat("Sum of squared differences to last variance estimates:",

+            signif(reweight.diff, 2), "\n")

+      }

+    }

+  }

+

   # We need to return some more data for summary and plotting

   fit$solution_type <- solution_type

 

@@ -214,19 +251,23 @@ mkinfit <- function(mkinmod, observed,
                                         mod_vars)

   bparms.all = c(bparms.optim, bparms.fixed)

 

-  # Collect observed, predicted and residuals

+  # Collect observed, predicted, residuals and weighting

   data <- merge(fit$observed, fit$predicted, by = c("time", "name"))

-  if (is.null(err)) {

-    names(data) <- c("time", "variable", "observed", "predicted")

-  } else {

-    names(data) <- c("time", "variable", "observed", "err", "predicted")

-  }

-  data$residual <- data$observed - data$predicted

-  data$variable <- ordered(data$variable, levels = obs_vars)

-  fit$data <- data[order(data$variable, data$time), ]

+  data$name <- ordered(data$name, levels = obs_vars)

+  data <- data[order(data$name, data$time), ]

+

+  fit$data <- data.frame(time = data$time,

+                         variable = data$name,

+                         observed = data$value.x,

+                         predicted = data$value.y)

+  fit$data$residual <- fit$data$observed - fit$data$predicted

+  if (!is.null(data$err.ini)) fit$data$err.ini <- data$err.ini

+  if (!is.null(err)) fit$data[[err]] <- data[[err]]

+

   fit$atol <- atol

   fit$rtol <- rtol

-  fit$weight <- ifelse(is.null(err), weight, "manual")

+  fit$weight.ini <- weight.ini

+  fit$reweight.method <- reweight.method

 

   # Return all backtransformed parameters for summary

   fit$bparms.optim <- bparms.optim 

@@ -282,7 +323,8 @@ summary.mkinfit <- function(object, data = TRUE, distimes = TRUE, alpha = 0.05,
 	  date.summary = date(),

 	  solution_type = object$solution_type,

 	  use_of_ff = object$mkinmod$use_of_ff,

-    weight = object$weight,

+    weight.ini = object$weight.ini,

+    reweight.method = object$reweight.method,

     residuals = object$residuals,

     residualVariance = resvar,

     sigma = sqrt(resvar),

@@ -329,8 +371,10 @@ print.summary.mkinfit <- function(x, digits = max(3, getOption("digits") - 3), .
   cat("\nMethod used for solution of differential equation system:\n")

   cat(x$solution_type, "\n")

 

-  cat("\nWeighting method:\n")

-  cat(x$weight, "\n")

+  cat("\nWeighting:", x$weight.ini)

+  if(!is.null(x$reweight.method)) cat(" then iterative reweighting method",

+                                      x$reweight.method)

+  cat("\n")

 

   cat("\nStarting values for optimised parameters:\n")

   print(x$start)