formula_lp {nomogramFormula}

Explore the Formula of Total Points and Linear Predictors

Description

Explore the formula of total points and linear predictors by the best power.

Usage

formula_lp(nomogram, power, digits = 6)

Arguments

nomogram

results of nomogram() function in 'rms' package

power

power can be automatically selected based on all R2 equal 1

digits

default is 6

Value

formula is the formula of total points and linear predictors. test is the R2 and RMSE which are used to test the fitted points. diff is difference between nomogram points and fitted points

Examples

library(rms)  # needed for nomogram
set.seed(2018)
n <-2019
age <- rnorm(n,60,20)
sex <- factor(sample(c('female','male'),n,TRUE))
sex <- as.numeric(sex)
weight <- sample(50:100,n,replace = TRUE)
time <- sample(50:800,n,replace = TRUE)
units(time)="day"
death <- sample(c(1,0,0),n,replace = TRUE)
df <- data.frame(time,death,age,sex,weight)
ddist <- datadist(df)
oldoption <- options(datadist='ddist')
f <- cph(formula(Surv(time,death)~sex+age+weight),data=df,
         x=TRUE,y=TRUE,surv=TRUE,time.inc=3)
surv <- Survival(f)
nomo <- nomogram(f,
                 lp=TRUE,
                 fun=list(function(x) surv(365,x),
                          function(x) surv(365*2,x)),
                 funlabel=c("1-Year Survival Prob",
                            "2-Year Survival Prob"))
options(oldoption)
formula_lp(nomogram = nomo)
formula_lp(nomogram = nomo,power = 1)
formula_lp(nomogram = nomo,power = 3,digits=6)