survPrep: Expand a data frame for survival analysis.

This is a utility function for preparing a data frame for survival analysis.

survPrep(df, timevar='t', statusvar='status')

Arguments

df	A data frame to expand for survival analysis. Must contain a variable with time points > 0, and a binary response column indicating whether the event was observed (1) or not (0) at the observed time. Defaults to NULL.
timevar	The name of the column in df containing time values. Defaults to 't'.
statusvar	The name of the column in df containing the binary response. Defaults to 'status'.

Value

surv

A data frame containing one row for every time point for every observation, up to the observed time for each observation. The statusvar is set to zero for all times before the observed time.

Examples

if (FALSE) {
   # Test data frame to illustrate.
   testdf = data.frame('id' = c(1,2,3,4,5),
                          't' = c(4,3,1,2,10),
                          'x' = c('a','b','c','d','e'),
                          'y' = c(0,1,1,0,1),
                          'z' = rnorm(5))

   # Create expanded data set.
   survdf = survPrep(testdf, 't', 'y')
}