How to place titles in lattice plots

I like the Economist theme in the latticeExtra package. It produces nice looking charts that mimic the design of the weekly newspaper, such as in this example:

For some time I wondered how I could put the title of my lattice plots into the top left corner as well (by default titles are centred). Reviewing the code of the theEconomist.theme function by Felix Andrews reveals the trick. It is the setting of par.

Combining several lattice charts into one

Last week I mentioned the grid.arrange function of the gridExtra package that allows me to combine graphical grid objects onto one page. The latticeExtra package provides another elegant solution for trellis (lattice) plots: the function c.trellis() or just c() combines the panels of multiple trellis objects into one. Here is minimal example from the help file of c.trellis: library(latticeExtra)

Combine different types of plots.

c(wireframe(volcano), contourplot(volcano))

In my next example I am using data from Eurostat, the statistical office of the European Union, showing the use of public transport in four countries.

Transforming subsets of data in R with by, ddply and data.table

Transforming data sets with R is usually the starting point of my data analysis work. Here is a scenario which comes up from time to time: transform subsets of a data frame, based on context given in one or a combination of columns. As an example I use a data set which shows sales figures by product for a number of years:df <- data.frame(Product=gl(3,10,labels=c(“A”,“B”, “C”)), Year=factor(rep(2002:2011,3)), Sales=1:30) head(df)

Product Year Sales

Waterfall charts in style of The Economist with R

Waterfall charts are sometimes quite helpful to illustrate the various moving parts in financial data, particularly when I have positive and negative values like a profit and loss statement (P&L). However, they can be a bit of a pain to produce in Excel. Not so in R, thanks to the waterfall package by James Howard. In combination with the latticeExtra package it is nearly a one-liner to produce a good looking waterfall chart that mimics the look of The Economist: