[R] modify strip labels with given text using lattice package

[David Winsemius]

On Aug 31, 2015, at 1:17 PM, Luigi Marongiu wrote:

> Dear all,
> I am drawing a barchart plot with lattice and the resulting strips are
> taking the value of the variable being compared (in this example
> "assay"). However I would like to write myself the value to place into
> the strips, let's say I want to call the variables as "molecular test"
> and "serological test" the values "a" and "b" respectively within
> "assay". I have tried different approaches taken from the web but
> nothing worked.

Look at ?barchart in the section on arguments to strip and then at ?strip.default for how to use `strip.custom`. If you needed finer control there are functions that return the panel, but this request did not require using it:

barchart(
   test ~ count|assay,
   df,
   groups = res,
   stack = TRUE,
   main = "Comparison of test results",
   xlab = "Count",
   col = c("yellow", "blue"),
   par.settings = list(
       strip.background = list(col="light grey"),
       superpose.polygon=list(col= c("yellow", "blue"))
   ),
   strip = strip.custom( factor.levels=c("molecular test","serological test") ),

   scales = list(
       alternating = FALSE
   ),
   key = list(
       space="top",
       columns=2,
       text=list(c("Negative", "Positive"), col="black"),
       rectangles=list(col=c("yellow", "blue"))
   )
)

> Would you have any tip?
> Best regards
> Luigi
> 
>>>> 
> test <- rep(c("Adenovirus", "Rotavirus", "Norovirus", "Rotarix",
> "Sapovirus"), 2)
> res <- c(0, 1, 0, 1,0, 1,0, 1,0, 1, 0, 1, 0, 1,0, 1,0, 1,0, 1)
> count <- rnorm(20)
> assay <- c(rep("a", 10), rep("b", 10))
> 
> df <- data.frame(test, res, count, assay, stringsAsFactors = FALSE)
> 
> library(lattice)
> barchart(
>    test ~ count|assay,
>    df,
>    groups = res,
>    stack = TRUE,
>    main = "Comparison of test results",
>    xlab = "Count",
>    col = c("yellow", "blue"),
>    par.settings = list(
>        strip.background = list(col="light grey"),
>        superpose.polygon=list(col= c("yellow", "blue"))
>    ),
>    scales = list(
>        alternating = FALSE
>    ),
>    key = list(
>        space="top",
>        columns=2,
>        text=list(c("Negative", "Positive"), col="black"),
>        rectangles=list(col=c("yellow", "blue"))
>    )
> )
> 
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David Winsemius
Alameda, CA, USA