R: Factors for person-year calculations

tcut {survival} | R Documentation

## Factors for person-year calculations

### Description

Attaches categories for person-year calculations to a variable without losing the underlying continuous representation

### Usage

    tcut(x, breaks, labels, scale=1)
    ## S3 method for class 'tcut'
    levels(x)

### Arguments

`x` | numeric/date variable
`breaks` | breaks between categories, which are right-continuous
`labels` | labels for categories
`scale` | Multiply `x` and `breaks` by this.

### Value

An object of class `tcut`

### See Also

`cut`, `pyears`

### 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

[Package survival version 3.2-7 Index]