daDoctoR/R/rep_lm.R
agdamsbo f807350a89 u
2018-10-04 21:06:22 +02:00

108 lines
2.7 KiB
R

#' A repeated linear regression function
#'
#' For bivariate analyses, to determine which variables to include in adjusted model.
#' @param meas Effect meassure. Input as c() of columnnames, use dput().
#' @param vars variables in model. Input as c() of columnnames, use dput().
#' @param string variables to test. Input as c() of columnnames, use dput().
#' @param ci flag to get results as OR with 95% confidence interval.
#' @param data data frame to pull variables from.
#' @keywords linear regression
#' @export
#' @examples
#' l<-50
#' y<-factor(rep(c("a","b"),l))
#' x<-rnorm(length(y), mean=50, sd=10)
#' v1<-factor(rep(c("r","s"),length(y)/2))
#' v2<-sample(1:100, length(y), replace=FALSE)
#' v3<-as.numeric(1:length(y))
#' d<-data.frame(y,x,v1,v2,v3)
#' preds<-c("v1","v2","v3")
#' rep_lm(meas="x",vars="y",string=preds,ci=F,data=d)
rep_lm<-function(meas,vars,string,ci=FALSE,data){
require(broom)
d<-data
x<-data.frame(d[,c(string)])
v<-data.frame(d[,c(vars)])
names(v)<-c(vars)
y<-d[,c(meas)]
dt<-cbind(y,v)
m1<-length(coef(lm(y~.,data = dt)))
if (is.factor(y)){stop("Some kind of error message would be nice, but y should not be a factor!")}
if (ci==TRUE){
df<-data.frame(matrix(NA,ncol = 3))
names(df)<-c("pred","or_ci","pv")
for(i in 1:ncol(x)){
dat<-cbind(dt,x[,i])
m<-lm(y~.,data=dat)
l<-suppressMessages(round(confint(m)[-c(1:m1),1],2))
u<-suppressMessages(round(confint(m)[-c(1:m1),2],2))
or<-round(coef(m)[-c(1:m1)],2)
or_ci<-paste0(or," (",l," to ",u,")")
pv<-round(tidy(m)$p.value[-c(1:m1)],3)
x1<-x[,i]
if (is.factor(x1)){
pred<-paste(names(x)[i],levels(x1)[-1],sep = "_")}
else {pred<-names(x)[i]}
df<-rbind(df,cbind(pred,or_ci,pv))}}
if (ci==FALSE){
df<-data.frame(matrix(NA,ncol = 3))
names(df)<-c("pred","b","pv")
for(i in 1:ncol(x)){
dat<-cbind(dt,x[,i])
m<-lm(y~.,data=dat)
b<-round(coef(m)[-c(1:m1)],3)
pv<-round(tidy(m)$p.value[-c(1:m1)],3)
x1<-x[,i]
if (is.factor(x1)){
pred<-paste(names(x)[i],levels(x1)[-1],sep = "_")
}
else {pred<-names(x)[i]}
df<-rbind(df,cbind(pred,b,pv))
}}
pa<-as.numeric(df[,3])
pa<-ifelse(pa<0.001,"<0.001",pa)
t <- ifelse(pa<=0.1|pa=="<0.001","include","drop")
pa <- ifelse(pa<=0.05|pa=="<0.001",paste0("*",pa),
ifelse(pa>0.05&pa<=0.1,paste0(".",pa),pa))
r<-data.frame(df[,1:2],pa,t)[-1,]
return(r)
}
l<-50
y<-factor(rep(c("a","b"),l))
x<-rnorm(length(y), mean=50, sd=10)
v1<-factor(rep(c("r","s"),length(y)/2))
v2<-sample(1:100, length(y), replace=FALSE)
v3<-as.numeric(1:length(y))
d<-data.frame(y,x,v1,v2,v3)
preds<-c("v1","v2","v3")
rep_lm(meas="x",vars="y",string=preds,ci=F,data=d)