Epi (version 0.7.0)

isec: Determine the intersection between follow-up intervals and a fixed interval.

Description

For a given piece of follow-up for ach person, this function determines the part of the follow-up which is inside a pre-specified interval. The function may occasionally be useful but is mainly included as a tool to be used in the function Lexis.

Usage

isec( enter, exit, fail = 0, int, cens.value = 0,
        Expand = 1:length(enter))

Arguments

enter

Numereical vector of entry times.

exit

Numerical vector of exit times.

fail

Vector of exit status, i.e. status at time exit

int

The fixed interval. Numerical vector of length 2.

cens.value

Censoring value. Numerical. If the person survives the fixed interval, this will be the value of the status indicator, Fail

Expand

Person id to be carried to the output

Value

• A matrix with columns Expand - person identification, Enter - date of entry into the interval, Exit - date of exit from the interval and Fail - status indicator.

See Also

Lexis, icut, fcut1, fcut, ex1

Examples

one <- round( runif( 15, 0, 15 ), 1 )
two <- round( runif( 15, 0, 15 ), 1 )
doe <- pmin( one, two )
dox <- pmax( one, two )
# Goofy data rows to test possibly odd behaviour
doe[1:3] <- dox[1:3] <- 8
dox[2] <- 6
dox[3] <- 7.5
# Some failure indicators
fail <- sample( 0:1, 15, replace=TRUE, prob=c(0.7,0.3) )
# So what have we got?
data.frame( doe, dox, fail )
# Find intersection with interval (4,8)
isec( doe, dox, fail, int=c(4,8) )
# See how it compares to original data
merge( data.frame( Expand=1:15, doe, dox, fail ),
       data.frame( isec( doe, dox, fail, int=c(4,8) ) ), all=TRUE )