### Name: tcut
### Title: Factors for person-year calculations
### Aliases: tcut [.tcut
### Keywords: survival

### ** Examples

mdy.date <- function(m,d,y)
   as.Date(paste(ifelse(y<100, y+1900, y), m, d, sep='/'))
temp1 <- mdy.date(6,6,36)
temp2 <- mdy.date(6,6,55)# Now compare the results from person-years
#
temp.age <- tcut(temp2-temp1, floor(c(-1, (18:31 * 365.24))),
        labels=c('0-18', paste(18:30, 19:31, sep='-')))
temp.yr  <- tcut(temp2, mdy.date(1,1,1954:1965), labels=1954:1964)
temp.time <- 3700   #total days of fu
py1 <- pyears(temp.time ~ temp.age + temp.yr, scale=1) #output in days
py1