# $Id$
# Copyright (C) 2010-2012 Johannes Ranke {{{
# Contact: jranke@uni-bremen.de
# This file is part of the R package mkin
# mkin is free software: you can redistribute it and/or modify it under the
# terms of the GNU General Public License as published by the Free Software
# Foundation, either version 3 of the License, or (at your option) any later
# version.
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
# details.
# You should have received a copy of the GNU General Public License along with
# this program. If not, see <http://www.gnu.org/licenses/> }}}
mkinmod <- function(..., use_of_ff = "min")
{
spec <- list(...)
obs_vars <- names(spec)
if (!use_of_ff %in% c("min", "max"))
stop("The use of formation fractions 'use_of_ff' can only be 'min' or 'max'")
# The returned model will be a list of character vectors, containing#{{{
# differential equations, parameter names and a mapping from model variables
# to observed variables. If possible, a matrix representation of the
# differential equations is included
parms <- vector()
diffs <- vector()
map <- list()#}}}
# Give a warning when a model with time dependent degradation uses formation#{{{
# fractions
if(spec[[1]]$type %in% c("FOMC", "DFOP", "HS")) {
mat = FALSE
if(!is.null(spec[[1]]$to)) {
message <- paste(
"Only constant formation fractions over time are implemented.",
"Depending on the reason for the time dependence of degradation",
"this may be unrealistic",
sep="\n")
warning(message)
} else message <- "ok"
} else mat = TRUE#}}}
# Establish list of differential equations as well as map from observed {{{
# compartments to differential equations
for (varname in obs_vars)
{
# Check the type component of the compartment specification {{{
if(is.null(spec[[varname]]$type)) stop(
"Every part of the model specification must be a list containing a type component")
if(!spec[[varname]]$type %in% c("SFO", "FOMC", "DFOP", "HS", "SFORB")) stop(
"Available types are SFO, FOMC, DFOP, HS and SFORB only")
if(spec[[varname]]$type %in% c("FOMC", "DFOP", "HS") & match(varname, obs_vars) != 1) {
stop(paste("Types FOMC, DFOP and HS are only implemented for the first compartment,",
"which is assumed to be the source compartment"))
} #}}}
# New (sub)compartments (boxes) needed for the model type {{{
new_boxes <- switch(spec[[varname]]$type,
SFO = varname,
FOMC = varname,
DFOP = varname,
HS = varname,
SFORB = paste(varname, c("free", "bound"), sep="_")
)
map[[varname]] <- new_boxes
names(map[[varname]]) <- rep(spec[[varname]]$type, length(new_boxes)) #}}}
# Start a new differential equation for each new box {{{
new_diffs <- paste("d_", new_boxes, " =", sep="")
names(new_diffs) <- new_boxes
diffs <- c(diffs, new_diffs) #}}}
} #}}}
# Create content of differential equations and build parameter list {{{
for (varname in obs_vars)
{
# Get the name of the box(es) we are working on for the decline term(s)
box_1 = map[[varname]][[1]] # This is the only box unless type is SFORB
if(spec[[varname]]$type %in% c("SFO", "SFORB")) { # {{{ Add SFO or SFORB decline term
if (use_of_ff == "min") { # Minimum use of formation fractions
# Turn on sink if this is not explicitly excluded by the user by
# specifying sink=FALSE
if(is.null(spec[[varname]]$sink)) spec[[varname]]$sink <- TRUE
if(spec[[varname]]$sink) {
# If sink is required, add first-order sink term
k_compound_sink <- paste("k", box_1, "sink", sep="_")
parms <- c(parms, k_compound_sink)
decline_term <- paste(k_compound_sink, "*", box_1)
} else { # otherwise no decline term needed here
decline_term = "0"
}
} else {
k_compound <- paste("k", box_1, sep="_")
parms <- c(parms, k_compound)
decline_term <- paste(k_compound, "*", box_1)
}
}#}}}
if(spec[[varname]]$type == "FOMC") { # {{{ Add FOMC decline term
# From p. 53 of the FOCUS kinetics report
decline_term <- paste("(alpha/beta) * ((time/beta) + 1)^-1 *", box_1)
parms <- c(parms, "alpha", "beta")
} #}}}
if(spec[[varname]]$type == "DFOP") { # {{{ Add DFOP decline term
# From p. 57 of the FOCUS kinetics report
decline_term <- paste("((k1 * g * exp(-k1 * time) + k2 * (1 - g) * exp(-k2 * time)) / (g * exp(-k1 * time) + (1 - g) * exp(-k2 * time))) *", box_1)
parms <- c(parms, "k1", "k2", "g")
} #}}}
if(spec[[varname]]$type == "HS") { # {{{ Add HS decline term
# From p. 55 of the FOCUS kinetics report
decline_term <- paste("ifelse(time <= tb, k1, k2)", "*", box_1)
parms <- c(parms, "k1", "k2", "tb")
} #}}}
# Add origin decline term to box 1 (usually the only box, unless type is SFORB)#{{{
diffs[[box_1]] <- paste(diffs[[box_1]], "-", decline_term)#}}}
if(spec[[varname]]$type == "SFORB") { # {{{ Add SFORB reversible binding terms
box_2 = map[[varname]][[2]]
if (use_of_ff == "min") { # Minimum use of formation fractions
k_free_bound <- paste("k", varname, "free", "bound", sep="_")
k_bound_free <- paste("k", varname, "bound", "free", sep="_")
parms <- c(parms, k_free_bound, k_bound_free)
reversible_binding_term_1 <- paste("-", k_free_bound, "*", box_1, "+",
k_bound_free, "*", box_2)
reversible_binding_term_2 <- paste("+", k_free_bound, "*", box_1, "-",
k_bound_free, "*", box_2)
} else { # Use formation fractions also for the free compartment
stop("The maximum use of formation fractions is not supported for SFORB models")
# The problems were: Calculation of dissipation times did not work in this case
# and the coefficient matrix is not generated correctly by the code present
# in this file in this case
f_free_bound <- paste("f", varname, "free", "bound", sep="_")
k_bound_free <- paste("k", varname, "bound", "free", sep="_")
parms <- c(parms, f_free_bound, k_bound_free)
reversible_binding_term_1 <- paste("+", k_bound_free, "*", box_2)
reversible_binding_term_2 <- paste("+", f_free_bound, "*", k_compound, "*", box_1, "-",
k_bound_free, "*", box_2)
}
diffs[[box_1]] <- paste(diffs[[box_1]], reversible_binding_term_1)
diffs[[box_2]] <- paste(diffs[[box_2]], reversible_binding_term_2)
} #}}}
# Transfer between compartments#{{{
to <- spec[[varname]]$to
if(!is.null(to)) {
# Name of box from which transfer takes place
origin_box <- box_1
# Add transfer terms to listed compartments
for (target in to) {
target_box <- switch(spec[[target]]$type,
SFO = target,
SFORB = paste(target, "free", sep="_"))
if (use_of_ff == "min" && spec[[varname]]$type %in% c("SFO",
"SFORB")) {
k_from_to <- paste("k", origin_box, target_box, sep="_")
parms <- c(parms, k_from_to)
diffs[[origin_box]] <- paste(diffs[[origin_box]], "-",
k_from_to, "*", origin_box)
diffs[[target_box]] <- paste(diffs[[target_box]], "+",
k_from_to, "*", origin_box)
} else {
fraction_to_target = paste("f", origin_box, "to", target, sep="_")
parms <- c(parms, fraction_to_target)
diffs[[target_box]] <- paste(diffs[[target_box]], "+",
fraction_to_target, "*", decline_term)
}
}
} #}}}
} #}}}
model <- list(diffs = diffs, parms = parms, map = map, use_of_ff = use_of_ff)
# Create coefficient matrix if appropriate#{{{
if (mat) {
boxes <- names(diffs)
n <- length(boxes)
m <- matrix(nrow=n, ncol=n, dimnames=list(boxes, boxes))
if (use_of_ff == "min") { # {{{ Minimum use of formation fractions
for (from in boxes) {
for (to in boxes) {
if (from == to) { # diagonal elements
k.candidate = paste("k", from, c(boxes, "sink"), sep="_")
k.candidate = sub("free.*bound", "free_bound", k.candidate)
k.candidate = sub("bound.*free", "bound_free", k.candidate)
k.effective = intersect(model$parms, k.candidate)
m[from,to] = ifelse(length(k.effective) > 0,
paste("-", k.effective, collapse = " "), "0")
} else { # off-diagonal elements
k.candidate = paste("k", from, to, sep="_")
if (sub("_free$", "", from) == sub("_bound$", "", to)) {
k.candidate = paste("k", sub("_free$", "_free_bound", from), sep="_")
}
if (sub("_bound$", "", from) == sub("_free$", "", to)) {
k.candidate = paste("k", sub("_bound$", "_bound_free", from), sep="_")
}
k.effective = intersect(model$parms, k.candidate)
m[to, from] = ifelse(length(k.effective) > 0,
k.effective, "0")
}
}
} # }}}
} else { # {{{ Use formation fractions where possible
for (from in boxes) {
for (to in boxes) {
if (from == to) { # diagonal elements
k.candidate = paste("k", from, sep="_")
m[from,to] = ifelse(k.candidate %in% model$parms,
paste("-", k.candidate), "0")
if(grepl("_free", from)) { # add transfer to bound compartment for SFORB
m[from,to] = paste(m[from,to], "-", paste("k", from, "bound", sep="_"))
}
if(grepl("_bound", from)) { # add backtransfer to free compartment for SFORB
m[from,to] = paste("- k", from, "free", sep="_")
}
m[from,to] = m[from,to]
} else { # off-diagonal elements
f.candidate = paste("f", from, "to", to, sep="_")
k.candidate = paste("k", from, to, sep="_")
# SFORB with maximum use of formation fractions not implemented, see above
m[to, from] = ifelse(f.candidate %in% model$parms,
paste(f.candidate, " * k_", from, sep=""),
ifelse(k.candidate %in% model$parms, k.candidate, "0"))
}
}
}
} # }}}
model$coefmat <- m
}#}}}
class(model) <- "mkinmod"
return(model)
}
# vim: set foldmethod=marker:
