Просто используйте rgb()
для своих цветов, четвертый аргумент - альфа:
library(tidyverse)
library(lattice)
tibble(
time = c(1,2,3,4,5),
var1 = c(2,2,2,2,1),
var2 = c(2,1,1,4,5)) %>%
barchart(var1 + var2 ~ time, data = .,
stack = TRUE, horiz = FALSE,
par.settings =
simpleTheme(
col = c(
rgb(1,0,0,0.2),
rgb(0,0,1,0.2)),
fill = c(
rgb(1,0,0,0.2),
rgb(0,0,1,0.2))),
auto.key = TRUE)