Extract time band data from a split Lexis object

Description

The break points of a Lexis object (created by a call to splitLexis) divide the follow-up intervals into time bands along a given time scale. The breaks function returns the break points, for a given time scale, and the timeBand classifies each row (=follow-up interval) into one of the time bands.

Usage

timeBand(lex, time.scale, type="integer")
breaks(lex, time.scale)

Arguments

Details

Time bands may be labelled in various ways according to the type argument. The permitted values of the type argument, and the corresponding return values are:

"integer"

a numeric vector with integer codes starting from 0.

"factor"

a factor (unordered) with labels "(left,right]"

"left"

the left-hand limit of the time band

"middle"

the midpoint of the time band

"right"

the right-hand limit of the time band

Value

The breaks function returns a vector of break points for the Lexis object, or NULL if no break points have been defined by a call to splitLexis. The timeBand function returns a numeric vector or factor, depending on the value of the type argument.

Note

A newly created Lexis object has no break points defined. In this case, breaks will return NULL, and timeBand will a vector of zeros.

Author(s)

Martyn Plummer

See Also

Lexis

Examples

data(diet)
diet <- cal.yr(diet)
diet.lex <- Lexis(entry=list(period=doe),
                   exit=list(period=dox, age=dox-dob),
            exit.status=chd,
                   data=diet)
diet.split <- splitLexis(diet.lex, breaks=seq(40,70,5), "age" )
age.left <- timeBand(diet.split, "age", "left")
table(age.left)
age.fact <- timeBand(diet.split, "age", "factor")
table(age.fact)
age.mid <- timeBand(diet.split, "age", "mid")
table(age.mid)

Results

R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

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> library(Epi)

Attaching package: 'Epi'

The following object is masked from 'package:base':

    merge.data.frame

> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/Epi/time.band.Rd_%03d_medium.png", width=480, height=480)
> ### Name: timeBand
> ### Title: Extract time band data from a split Lexis object
> ### Aliases: timeBand breaks
> ### Keywords: attribute
> 
> ### ** Examples
> 
> data(diet)
> diet <- cal.yr(diet)
> diet.lex <- Lexis(entry=list(period=doe),
+                    exit=list(period=dox, age=dox-dob),
+             exit.status=chd,
+                    data=diet)
> diet.split <- splitLexis(diet.lex, breaks=seq(40,70,5), "age" )
> age.left <- timeBand(diet.split, "age", "left")
> table(age.left)
age.left
-Inf   40   45   50   55   60   65 
  26   78  195  238  272  237  149 
> age.fact <- timeBand(diet.split, "age", "factor")
> table(age.fact)
age.fact
(-Inf,40]   (40,45]   (45,50]   (50,55]   (55,60]   (60,65]   (65,70]  (70,Inf] 
       26        78       195       238       272       237       149         0 
> age.mid <- timeBand(diet.split, "age", "mid")
> table(age.mid)
age.mid
-Inf 42.5 47.5 52.5 57.5 62.5 67.5 
  26   78  195  238  272  237  149 
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>