R/dfnsuniv.R

In smoothHR: Smooth Hazard Ratio Curves Taking a Reference Value

dfnsuniv <- function(time, time2=NULL, status, nl.predictor, other.predictors, method, maxdf=NULL, data) {
	options(warn=-1);
	ctype <- "FALSE";
	if ( missing(data) ) {stop("The argument data is missing");}
	if ( missing(time) ) {stop("The argument time is missing");}
	if ( missing(status) ) {stop("The argument status is missing");}
	if ( missing(nl.predictor) ) {stop("The argument 'nl.predictor' is missing");}
	if ( !missing(time2) ) {ctype <- "TRUE";}
	if ( missing(method) ) {method <- "AIC";}
	if ( missing(maxdf) ) {maxdf <- 15;}
	if ( method != "AIC" & method != "AICc" & method != "BIC") {stop("The argument 'method' is not valid");}
	p0 <- match(names(data), time, nomatch=0);
	p1 <- which(p0==1);
	ntime <- data[,p1];
	p2 <- match(names(data), status, nomatch=0);
	p3 <- which(p2==1);
	nstatus <- data[,p3];
	if (ctype == TRUE) {
		p2 <- match(names(data), time2, nomatch=0);
		p3 <- which(p2 == 1);
		ntime2 <- data[,p3];
	}
	myaic <- vector(length=maxdf);
	if ( !missing(other.predictors) ) {opred <- paste(other.predictors, collapse="+");}
	if (ctype == "TRUE") {
		p4 <- match(names(data), time2, nomatch=0);
		p5 <- which(p4 == 1);
		ntime2 <- data[,p5];
	}
	for ( k in 1:as.integer(maxdf) ) {
		npred1 <- paste("ns(", nl.predictor, ", df=", k, ")");
		if ( !missing(other.predictors) ) {pred <- paste(npred1, opred, sep="+");}
		else {pred <- npred1;}
		#pred <- paste("ns(", predictor, ", df=", k, ")");
		if (ctype == "TRUE") {
			covar <- as.formula( paste(" Surv(ntime,ntime2,nstatus)~ ", pred) );
			try(fit1 <- coxph(covar, data=data, x=TRUE), TRUE);
		} else {
			covar <- as.formula( paste(" Surv(ntime,nstatus)~ ", pred) );
			try(fit1 <- coxph(covar, data=data, x=TRUE), TRUE);
		}
		if (method == "AIC") {try(myaic[k] <- -2*fit1$loglik[2]+2*k, TRUE);}
		else if (method == "AICc") {try(myaic[k] <- -2*fit1$loglik[2]+2*fit1$nevent*(k+1)/(fit1$nevent-k-2), TRUE);}
		else if (method == "BIC") {try(myaic[k] <- -2*fit1$loglik[2]+2*log(fit1$nevent)*k, TRUE);}
	}
	df <- which.min(myaic);
	options(warn=0);
	return(df);
} # dfnsuniv