bar = function()
{
	barchart(yield ~ variety | site, data = barley,
	#barchart(yield ~ variety , data = barley,
	groups = year, layout = c(1,6), stack = TRUE,
	auto.key = list(space = "right"),
	ylab = "Barley Yield (bushels/acre)",
	scales = list(x = list(rot = 45)))
}

# How to allow for either the first barchart or the second one? 
# Use a conditional

bar1 = function(which=1, factor=barley$site)
{
	if (which == 1) {
		barchart(yield ~ variety | factor, data = barley,
		groups = year, layout = c(1,6), stack = TRUE,
		auto.key = list(space = "right"),
		ylab = "Barley Yield (bushels/acre)",
		scales = list(x = list(rot = 45)))
	} else {
		barchart(yield ~ variety , data = barley,
		groups = year, layout = c(1,6), stack = TRUE,
		auto.key = list(space = "right"),
		ylab = "Barley Yield (bushels/acre)",
		scales = list(x = list(rot = 45)))
	}
}


# NOTE USE OF
#   groups  (factor within a bar)
#   | factor : number of individual plots