Epi: start.Lexis – R documentation

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Epi

start.Lexis

Time series and other methods for Lexis objects

Description

Extract the entry time, exit time, status or duration of follow-up from a Lexis object. Classify states.

Usage

entry( x, time.scale = NULL, by.id=FALSE )
      exit( x, time.scale = NULL, by.id=FALSE )
    status( x, at="exit"        , by.id=FALSE )
       dur( x,                    by.id=FALSE )
 transient( x )
 absorbing( x )
 preceding( x, states )
    before( x, states )
succeeding( x, states )
     after( x, states )

Arguments

`x`	an object of class `Lexis`.
`time.scale`	a string or integer indicating the time scale. If omitted, all times scales are used.
`by.id`	Logical, if `TRUE`, only one record per unique value of `lex.id` is returned; either the first, the last, or for `dur`, the sum of `lex.dur`. If `TRUE`, the returned object have the `lex.id` as (row)names attribute.
`at`	string indicating the time point(s) at which status is to be measured. Possible values are "exit" or "entry".
`states`	Character vector of states.

Value

The entry and exit functions return a vector of entry times and exit times, respectively, on the requested time scale. If multiple time scales are requested, a matrix is returned.

The status function returns a vector giving the status at "at" (either 'entry' or 'exit') and dur returns a vector with the lengths of the follow-up intervals.

entry, exit, status and dur return vectors of length nrow(x) if by.id=FALSE; if by.id=TRUE a vector of length length(unique(lex.id)).

The functions transient and absorbing return character vectors of the transient, resp. absorbing states in x. These are necessariy disjoint but the union may be a proper subset of levels(x), since the latter may have levels that are never assumed by either lex.Cst or lex.Xst.

preceding returns a character vector with names of the states of the Lexis object x from which one of the states in states can be reached directly - the preceding states. before is just a synonym for preceding.

succeeding returns a character vector with names of the states of the Lexis object x that can be reached directly from one of the states in states. after is just a synonym for succeeding.

Author(s)

Martyn Plummer & Bendix Carstensen