Martin Maechler's TODO list for R

This page contains (some of) my plans for enhancements to R ... with absolutely no warranty ...
You might also be interested in things no longer on the current list below.

Martin Maechler maechler@r-project.org

Shorter term

• Improve pair() to allow spreading over a few pages ("wall paper" :-) {a bit as lag.plot() (from the ts package) does}. Improve it along the lines of Catherine Hurley (even much easier)
• plot.factor() should *not* do boxplots by default when the boxplot contains less than or only about 5-7 observations!
• Extend box() to also accept 'bg' and draw backgrounds using GRect(). box(bg="green3") will then be a higher level alternative to (code from demo(graphics)!)

       usr <- par("usr")
       rect(usr[1], usr[3], usr[2], usr[4], col="green3")
       box()
       

• The dendrogram class {package "stats"} needs better and more versatile methods, particularly plot.*().
  One application is for the VLMC package available from CRAN. Here, do as.dendrogram.VLMC() properly and implement plot.VLMC() basically doing plot.dendrogram( as.dendrogram.VLMC( * ) ).
  (done in parts for R 1.9.0; more todo)
• Minimum Spanning Tree: two versions (maybe in one function):
  
  1. mstree() using Euclidean distance and the usual n x p data matrix. Robert has a simple mstree() in his unofficial Genecluster package in bioconductor {though lacking Friedman/Rafsky's planing option} which should be easy to put into 'stats' as is.
  2. I really want to compute the general MST problem (i.e. given an arbitrary graph with weighted edges, find a subgraph which is a tree with minimal edge weight sum). The typical application I have in mind would still be graphs with many edges, i.e. almost complete ones.
• procrustes() is wanted, but not just the two sample case, and (eventually at least) also with case and variable weighting.
• Extend the Guidelines for Rd files, (say more about \item in \arguments, also recommendation/examples about the usage of \describe) and think about merging (or moving) parts into the Writing R Extensions manual which is part of R, or available from the CRAN Manuals.
• cov.wt() should also work with NA's, with a `use' argument identical to cov(), cor(); Using a notion of "generalized ranks", maybe could also grow "spearman" and "kendall" methods.
• str() for lists (and data.frames) should get an option to allow numbering the list components (maybe via a smart specification of the indent.str argument).

Of less priority

• Need C API for the Median() and more generally quantile(x, alpha). (not sure anymore; we have a C API to partial sorting)
• stem() should exclude outliers and list them separately (as S does).
• New print option for printing exact "0"s:
  Consider using "." instead of "0" in numerical matrices. This would make sparse matrices much more readable. [I have been doing this with S-plus for years.]
• scat1d() {improved rug(); the thing I've co-authored and has then been put into Hmisc}.

Even Longer Term

• Differential Equation Solvers; I need a boundary value problem solver, additional to the LSODA functionality of the very good odesolve package available from CRAN.

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