Adding labels within lattice panels by group

18 Feb 2014 Graphics

The other day I had data that showed the development of many products over time. I grouped the products into categories and visualised the data as line graphs in lattice. But instead of adding an extensive legend to the plot I wanted to add labels to each line’s latest point. How do you do that? It turns out that panel.groups is there to help again.

Here is my solution:

R code

	set.seed(12345)
	dat <- data.frame(category=rep(c("Food", "Drinks"),20),
	product=rep(c("Cheese", "Wine", "Bread", "Beer"), 10),
	year=sort(rep(c(2004:2013),4)),
	value=sort(rnorm(40)))

	dat <- dat[with(dat, order(category, year)),]

	library(lattice)
	# Change some of the default lattice settings
	my.settings <- canonical.theme(color=FALSE)
	my.settings[['strip.background']]$col <- "black"
	my.settings[['strip.border']]$col<- "black"
	xyplot(value ~ year \| category,
	groups=product, data=dat,
	as.table=TRUE,
	xlim=c(2003, 2016), # range of x-axis
	scales=list(cex=c(1.1, 1.1), # increase font size
	alternating=1, # axes labels left/bottom
	tck = c(1,0)), # ticks only with labels
	par.settings = my.settings,
	cex=1.1, # change size of symbols
	xlab=list(label="Year", fontsize=14),
	ylab=list(label="Value", fontsize=14),
	par.strip.text=list(col="white", font=2),
	panel=panel.superpose,
	panel.groups=function(x,y, group.number,...){
	panel.xyplot(x,y,t="b",...)
	panel.grid(v=-1, h=-1, lty=3)
	xt <- x[x==max(x)] # find latest year
	yt <- y[x==max(x)] # find value at latest year
	panel.text(xt, yt, labels=levels(dat$product)[group.number],
	pos=4, # show labels on right side
	...)
	}
	)

view raw labels_in_panels.R hosted with ❤ by GitHub

Session Info

R version 3.0.2 (2013-09-25)
Platform: x86_64-apple-darwin10.8.0 (64-bit)

locale:
[1] en_GB.UTF-8/en_GB.UTF-8/en_GB.UTF-8/C/en_GB.UTF-8/en_GB.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] lattice_0.20-24

loaded via a namespace (and not attached):
[1] grid_3.0.2

Citation

For attribution, please cite this work as:

Markus Gesmann (Feb 18, 2014) Adding labels within lattice panels by group. Retrieved from https://magesblog.com/post/2014-02-18-adding-labels-within-lattice-panels-by/

BibTeX citation:

@misc{ 2014-adding-labels-within-lattice-panels-by-group,
author = { Markus Gesmann },
title = { Adding labels within lattice panels by group },
url = { https://magesblog.com/post/2014-02-18-adding-labels-within-lattice-panels-by/ },
year = { 2014 }
updated = { Feb 18, 2014 }
}

panel.groups lattice R legend

Adding labels within lattice panels by group

R code

Session Info

Citation

Markus Gesmann

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