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 ...

Waterfall charts are sometimes quite helpful to illustrate the various moving parts in financial data, in particular where 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 Ex...