splitLexisDT: Split case-level observations

In popEpi: Functions for Epidemiological Analysis using Population Data

Split case-level observations

Description

Split a Lexis object along one time scale (as ⁠[Epi::splitLexis]⁠) with speed

Usage

splitLexisDT(lex, breaks, timeScale, merge = TRUE, drop = TRUE)

Arguments

lex	a Lexis object, split or not
breaks	a vector of ⁠[a,b)⁠ breaks to split data by
timeScale	a character string; name of the time scale to split by
merge	logical; if TRUE, retains all variables from the original data - i.e. original variables are repeated for all the rows by original subject
drop	logical; if TRUE, drops all resulting rows after expansion that reside outside the time window defined by the given breaks

Details

splitLexisDT is in essence a data.table version of splitLexis or survSplit for splitting along a single time scale. It requires a Lexis object as input, which may have already been split along some time scale.

Unlike splitLexis, splitLexisDT drops observed time outside the roof and floor of breaks by default - with drop = FALSE the functions have identical behaviour.

The Lexis time scale variables can be of any arbitrary format, e.g. Date, fractional years (see ⁠[Epi::cal.yr]⁠) and ⁠[get.yrs]⁠.

Value

A data.table or data.frame (depending on options("popEpi.datatable"); see ?popEpi) object expanded to accommodate split observations.

Author(s)

Joonas Miettinen

See Also

Other splitting functions: lexpand(), splitMulti()

Examples

library(Epi)
data("sire", package = "popEpi")
x <- Lexis(data=sire[1000:1100, ],
           entry = list(fot=0, per=get.yrs(dg_date), age=dg_age),
           exit=list(per=get.yrs(ex_date)), exit.status=status)
BL <- list(fot=seq(0, 5, by = 3/12), per=c(2008, 2013))

x2 <- splitMulti(x, breaks = BL, drop = FALSE)

x3 <- splitLexisDT(x, breaks = BL$fot, timeScale = "fot", drop = FALSE)
x3 <- splitLexisDT(x3, breaks = BL$per, timeScale = "per", drop = FALSE)

x4 <- splitLexis(x,  breaks = BL$fot, time.scale = "fot")
x4 <- splitLexis(x4, breaks = BL$per, time.scale = "per")
## all produce identical results

## using Date variables
x <- Lexis(data=sire[1000:1100, ],
           entry = list(fot=0, per=dg_date, age=dg_date-bi_date),
           exit=list(per=ex_date), exit.status=status)
BL <- list(fot = 0:5*365.25, per = as.Date(c("2008-01-01", "2013-01-01")))

x2 <- splitMulti(x, breaks = BL, drop = FALSE)

x3 <- splitLexisDT(x, breaks = BL$fot, timeScale = "fot", drop = FALSE)
x3 <- splitLexisDT(x3, breaks = BL$per, timeScale = "per", drop = FALSE)

## splitLexis may not work when using Dates

popEpi documentation built on April 4, 2025, 2:51 a.m.