Convert a survival dataset in wide format (with numbers of survivors in columns) to a list with variables 'time' and 'event' as required for survival analysis in R.

toSurv.R

toSurv <- function(data, times){
  
  if(ncol(data)!=length(times)){
    stop("'data' and 'time' must be equal in length.")
  }
  
  last <- ncol(data)
  
  eventlist <- timelist <- list()
  
  for(r in 1:nrow(data)){
    da <- as.numeric(data[r, ])
    begin <- da[1]
    end <- da[last]
    dd <- numeric(length(da) - 1)
    for(i in 2:length(da)){
      dd[i] <- -1 * (da[i] - da[i - 1])
    }
    timelist[[r]] <- c(rep(times, dd), rep(last, end))
    eventlist[[r]] <- c(rep(1, sum(dd)), rep(0, end))
  }
  
  return(list(time=unlist(timelist), event=unlist(eventlist)))
  
}

# A toy example
DATA <- rbind(c(20, 20, 19, 16, 15, 13, 11),
              c(20, 19, 17, 15, 12, 11, 10),
              c(20, 19, 17, 17, 13, 11, 9))
TIME <- 1:7
toSurv(DATA, TIME)