Question

I have a lattice graph with two conditions: one condition (x1) has 4 levels and one has 2 levels (x2). The graph has a stripes for each variable x1 and x2:

df <- data.frame(y = runif(100,0,10)
                 , x1 = rep(c("A","B","C","D"),25)
                 , x2 = as.numeric(c(runif(100)<0.5))
                 )
histogram( ~y | x1 + as.factor(x2), data=df)

I would like to change the levels of x1.

I tried with:

histogram( ~y | x1 + as.factor(x2)      
          , data=df
          , strip = strip.custom(
                     , factor.levels = c("no","yes"))
                     )
)

but I don’t konw how to assign the levels condition x2. I appreciate any hint.

Answer 1

Searching the web found solution defining own strip function.

my.strip <- function(which.given, ..., factor.levels) {
             levs <- if (which.given == 2) c("no","yes") #levels for your second factor (x2)
                      else c("AAA", "BBB", "CCC", "DDD") #levels for your first factor (x1)
              strip.default(which.given, ..., factor.levels = levs)
           }

histogram( ~y | x1 + as.factor(x2) , data=df, strip = my.strip)

EDIT – define own strips using useOuterStrips()

library(latticeExtra)
useOuterStrips(histogram( ~y | x1 + as.factor(x2) , data=df), 
               strip =strip.custom(factor.levels = c("AAA","BBB","CCC","DDD")),
               strip.left=strip.custom(factor.levels = c("no","yes")))