Revision 69b0f9dca8eb051f132725ecc679fe1997246e50 authored by Adrian Baddeley on 18 January 2006, 21:47:25 UTC, committed by cran-robot on 18 January 2006, 21:47:25 UTC
1 parent cb2215f
mpl.R
# mpl.R
#
# $Revision: 5.19 $ $Date: 2005/04/12 20:27:05 $
#
# mpl.engine()
# Fit a point process model to a two-dimensional point pattern
# by maximum pseudolikelihood
#
# mpl.prepare()
# set up data for glm procedure
#
# -------------------------------------------------------------------
#
"mpl" <- function(Q,
trend = ~1,
interaction = NULL,
data = NULL,
correction="border",
rbord = 0,
use.gam=FALSE) {
.Deprecated("ppm", package="spatstat")
ppm(Q, trend, interaction, data, correction, rbord, use.gam, method="mpl")
}
"mpl.engine" <-
function(Q,
trend = ~1,
interaction = NULL,
covariates = NULL,
correction="border",
rbord = 0,
use.gam=FALSE,
forcefit=FALSE
) {
#
# Extract quadrature scheme
#
if(verifyclass(Q, "ppp", fatal = FALSE)) {
# warning("using default quadrature scheme")
Q <- quadscheme(Q)
} else if(!verifyclass(Q, "quad", fatal=FALSE))
stop("First argument Q should be a quadrature scheme")
#
# Data points
X <- Q$data
#
# Data and dummy points together
P <- union.quad(Q)
#
#
# Interpret the call
want.trend <- !is.null(trend) && !identical.formulae(trend, ~1)
want.inter <- !is.null(interaction) && !is.null(interaction$family)
the.version <- list(major=1,
minor=5,
release=7,
date="$Date: 2005/04/12 20:27:05 $")
if(use.gam && exists("is.R") && is.R())
require(mgcv)
if(!want.trend && !want.inter && !forcefit) {
# the model is the uniform Poisson process
# The MPLE (= MLE) can be evaluated directly
npts <- X$n
volume <- area.owin(X$window) * markspace.integral(X)
lambda <- npts/volume
theta <- list("log(lambda)"=log(lambda))
maxlogpl <- npts * (log(lambda) - 1)
rslt <- list(
method = "mpl",
theta = theta,
coef = theta,
trend = NULL,
interaction = NULL,
Q = Q,
maxlogpl = maxlogpl,
internal = list(),
covariates = NULL,
correction = correction,
rbord = rbord,
version = the.version)
class(rslt) <- "ppm"
return(rslt)
}
################# P r e p a r e D a t a ######################
prep <- mpl.prepare(Q, X, P, trend, interaction,
covariates, want.trend, want.inter, correction, rbord)
fmla <- prep$fmla
glmdata <- prep$glmdata
################# F i t i t ####################################
# Fit the generalized linear/additive model.
if(want.trend && use.gam)
FIT <- gam(fmla, family=quasi(link=log, var=mu), weights=.mpl.W,
data=glmdata, subset=(.mpl.SUBSET=="TRUE"),
control=gam.control(maxit=50))
else
FIT <- glm(fmla, family=quasi(link=log, var=mu), weights=.mpl.W,
data=glmdata, subset=(.mpl.SUBSET=="TRUE"),
control=glm.control(maxit=50))
################ I n t e r p r e t f i t #######################
# Fitted coefficients
co <- FIT$coef
theta <- if(exists("is.R") && is.R()) NULL else dummy.coef(FIT)
W <- glmdata$.mpl.W
SUBSET <- glmdata$.mpl.SUBSET
Z <- is.data(Q)
Vnames <- prep$Vnames
# attained value of max log pseudolikelihood
maxlogpl <- -(deviance(FIT)/2 + sum(log(W[Z & SUBSET])) + sum(Z & SUBSET))
######################################################################
# Clean up & return
rslt <- list(
method = "mpl",
theta = theta,
coef = co,
trend = if(want.trend) trend else NULL,
interaction = if(want.inter) interaction else NULL,
Q = Q,
maxlogpl = maxlogpl,
internal = list(glmfit=FIT, glmdata=glmdata, Vnames=Vnames),
covariates = covariates,
correction = correction,
rbord = rbord,
version = the.version)
class(rslt) <- "ppm"
return(rslt)
}
##########################################################################
### /////////////////////////////////////////////////////////////////////
##########################################################################
mpl.prepare <- function(Q, X, P, trend, interaction, covariates,
want.trend, want.inter, correction, rbord, ...) {
if(missing(want.trend))
want.trend <- !is.null(trend) && !identical.formulae(trend, ~1)
if(missing(want.inter))
want.inter <- !is.null(interaction) && !is.null(interaction$family)
# Validate/evaluate covariates
if(want.trend && !is.null(covariates))
covariates.df <- mpl.get.covariates(covariates, P, "quadrature points")
################ C o m p u t e d a t a ####################
### Form the weights and the ``response variable''.
.mpl <- list()
.mpl$W <- w.quad(Q)
.mpl$Z <- is.data(Q)
.mpl$Y <- .mpl$Z/.mpl$W
.mpl$MARKS <- marks.quad(Q) # is NULL for unmarked patterns
glmdata <- data.frame(.mpl.W = .mpl$W,
.mpl.Y = .mpl$Y)
n <- nrow(glmdata)
.mpl$SUBSET <- rep(TRUE, n)
internal.names <- c(".mpl.W", ".mpl.Y", ".mpl.Z", ".mpl.SUBSET",
"SUBSET", ".mpl")
reserved.names <- c("x", "y", "marks", internal.names)
zeroes <- attr(.mpl$W, "zeroes")
if(!is.null(zeroes))
.mpl$SUBSET <- !zeroes
####################### T r e n d ##############################
check.clashes <- function(forbidden, offered, where) {
name.match <- outer(forbidden, offered, "==")
if(any(name.match)) {
is.matched <- apply(name.match, 2, any)
matched.names <- (offered)[is.matched]
if(sum(is.matched) == 1) {
return(paste("The variable \"",
matched.names,
"\" in ", where,
" is a reserved name", sep=""))
} else {
return(paste("The variables \"",
paste(matched.names, collapse="\", \""),
"\" in ", where,
" are reserved names", sep=""))
}
}
return("")
}
if(want.trend) {
# Check for use of internal names in trend
cc <- check.clashes(internal.names, termsinformula(trend),
"the model formula")
if(cc != "") stop(cc)
# Default explanatory variables for trend
glmdata <- data.frame(glmdata, x=P$x, y=P$y)
if(!is.null(.mpl$MARKS))
glmdata <- data.frame(glmdata, marks=.mpl$MARKS)
#
if(!is.null(covariates)) {
# Check for duplication of reserved names
cc <- check.clashes(reserved.names, names(covariates), "\'covariates\'")
if(cc != "") stop(cc)
# Append `covariates.df' to `glmdata'
glmdata <- data.frame(glmdata,covariates.df)
}
}
###################### I n t e r a c t i o n ####################
Vnames <- NULL
if(want.inter) {
verifyclass(interaction, "interact")
# Calculations require a matrix (data) x (data + dummy) indicating equality
E <- equals.quad(Q)
# Form the matrix of "regression variables" V.
# The rows of V correspond to the rows of P (quadrature points)
# while the column(s) of V are the regression variables (log-potentials)
V <- interaction$family$eval(X, P, E,
interaction$pot,
interaction$par,
correction, ...)
if(!is.matrix(V))
stop("interaction evaluator did not return a matrix")
# Augment data frame by appending the regression variables for interactions.
#
# If there are no names provided for the columns of V,
# call them "Interact.1", "Interact.2", ...
if(is.null(dimnames(V)[[2]])) {
# default names
nc <- ncol(V)
dimnames(V) <- list(dimnames(V)[[1]],
if(nc == 1) "Interaction" else paste("Interact.", 1:nc, sep=""))
}
# List of interaction variable names
Vnames <- dimnames(V)[[2]]
# Check for name clashes between the interaction variables
# and the formula
cc <- check.clashes(Vnames, termsinformula(trend), "model formula")
if(cc != "") stop(cc)
# and with the variables in 'covariates'
if(!is.null(covariates)) {
cc <- check.clashes(Vnames, names(covariates), "\'covariates\'")
if(cc != "") stop(cc)
}
# OK. append variables.
glmdata <- data.frame(glmdata, V)
# Keep only those quadrature points for which the
# conditional intensity is nonzero.
#KEEP <- apply(V != -Inf, 1, all)
.mpl$KEEP <- matrowall(V != -Inf)
.mpl$SUBSET <- .mpl$SUBSET & .mpl$KEEP
if(any(.mpl$Z & !.mpl$KEEP)) {
howmany <- sum(.mpl$Z & !.mpl$KEEP)
warning(paste(howmany, "data point(s) are illegal (zero conditional intensity under the model)"))
# browser()
}
}
################## D a t a f r a m e ###################
# Determine the domain of integration for the pseudolikelihood.
if(correction == "border") {
bd <- bdist.points(P)
.mpl$DOMAIN <- (bd >= rbord)
.mpl$SUBSET <- .mpl$DOMAIN & .mpl$SUBSET
}
glmdata <- data.frame(glmdata, .mpl.SUBSET=.mpl$SUBSET)
################# F o r m u l a ##################################
if(!want.trend) trend <- ~1
trendpart <- paste(as.character(trend), collapse=" ")
rhs <- paste(c(trendpart, Vnames), collapse= "+")
fmla <- paste(".mpl.Y ", rhs)
fmla <- as.formula(fmla)
####
return(list(fmla=fmla, glmdata=glmdata, Vnames=Vnames))
}
####################################################################
####################################################################
mpl.get.covariates <- function(covariates, locations, type="") {
x <- locations$x
y <- locations$y
if(is.null(x) || is.null(y)) {
xy <- xy.coords(locations)
x <- xy$x
y <- xy$y
}
if(is.null(x) || is.null(y))
stop("Can't interpret \`locations\' as x,y coordinates")
n <- length(x)
if(is.data.frame(covariates)) {
if(nrow(covariates) != n)
stop(paste("Number of rows in \`covariates\' != number of", type))
return(covariates)
} else if(is.list(covariates)) {
if(!all(unlist(lapply(covariates, is.im))))
stop("Some entries in the list \`covariates\' are not images")
if(any(names(covariates) == ""))
stop("Some entries in the list \`covariates\' are un-named")
# look up values of each covariate image at the quadrature points
values <- lapply(covariates, lookup.im, x=x, y=y, naok=TRUE)
return(as.data.frame(values))
} else
stop("\`covariates\' must be either a data frame or a list of images")
}
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