RG#8: multiple arranged error bar plot (trallis type)

 # multiple arranged error bar plot (trallis type)
#data
env <- c(rep("E1", 9), rep("E2", 9))
trt <- c(rep (c("A101", "B234", "c777"), each = 3))
group <- c(rep (1:3, 6))
yld <- c(3,4,6, 3,8,4, 1,2,6, 3,4,5, 6,7,7, 1,4,8)
se <- c(0.3, 0.6, 0.3, 0.6, 0.1, 0.9, 0.21, 0.4,
    0.5, 0.2, 0.1, 0.3, 0.4, 0.2, 0.3, 0.4, 0.4, 0.3)
dataf <- data.frame (env, trt, group, yld, se)
limits <- aes(ymax = yld + se, ymin=yld - se)


# using ggplot2
require(ggplot2)
plt1 <- ggplot(dataf, aes(fill=factor(group), y=yld, x=trt))
plt1 + geom_bar(position= position_dodge(width=0.9)) +
geom_errorbar(limits, position= position_dodge(width=0.9), width=0.8) +
theme_bw( ) + facet_grid(.~env)