swap

	-b	The formula for facets.[${bldred}Default no facets, 
		+facet_grid(level ~ .) means divide by levels of 'level' vertcally.
		+facet_grid(. ~ level) means divide by levels of 'level' horizontally.
		+facet_grid(lev1 ~ lev2) means divide by lev1 vertically and lev2
		horizontally.
		+facet_wrap(~level, ncol=2) means wrap horizontally with 2
		columns.
		Example: +facet_wrap(~Size,ncol=6,scale='free')
		${txtrst}]
	-d	If facet is given, you may want to specifize the order of
		variable in your facet, default alphabetically.
		[${txtred}Accept sth like 
		(one level one sentence, separate by';') 
		data\$size <- factor(data\$size, levels=c("l1",
		"l2",...,"l10"), ordered=T) ${txtrst}]