Lately, I have been using R heavily for my analysis of how Github pull requests work (more on that in upcoming posts). It is not the first time I 've used R; the data analysis work in my PhD thesis was also done with R, while I used R for the occasional correlation or plot in other papers. However, I never had to manipulate data and design code that will be re-used (hopefully) with it.

The experience has not been great. The R language may be nice and fine for statisticians (I believe; I don't know any statistician), but from my perspective, it is a nightmare. While other languages may feel like they have designed by a committee, the R language seems to be designed by no-one. In my eyes, it looks like that every time someone needed a feature to be implemented, she just did and it stuck. The main problem is inconsistency, for example:

  • There are several ways to access a column in a dataframe. There are even more ways to select specific rows and columns.

  • Functions do not maintain a consistent parameter order. For example, in lapply the array to loop over is passed first while in the semantically equivalent Map (why the capital case?) it is second.

Moreover, R is extremely slow and inefficient. I have been using a data sample of 40,000 data points, moderate by any account, to build classifiers based on the Random Forest classification algorithm. The memory usage could easily reach 3-4 GBs (for just 5 MB of data and in-memory data structures), forcing me to run my experiments on a server, rather than my laptop. It takes R 3 min 15 sec to read a 35MB CSV file in memory and then it consumes more than 500MB of RAM.

What I would expect from a sane statistics language

I would like a statistics language that is also a data manipulation and exploration language. An ideal language, at least for the use cases I can think of now would have:

  • A uniform way to describe all (tabular) data. There is really no need for multiple data.frame like types (lists, vectors or matrices). A single type with support for unboxing (to enable fast matrix operations) should be enough.

  • A few numeric data types (infinite precision integers and floats), along data types for ordinal and categorical data. Memory efficient, UTF8-based strings.

  • Manipulation of data through higher order functions. LINQ has shown how this can be done with any data structure.

  • Optional typing. R and SciPy's lack of types are great for prototyping and fast testing on the REPL loop, but when real data need to be processed, types help a lot with consistency and optimization. Dart has shown that it can be practical.

  • A compiler to machine code or to an intermediate format able to produce efficient machine code (LLVM or JVM bytecode). Big data cannot be processed by interpreters and having to develop the same program twice (prototype with R, production in C++) is suboptimal.

  • A library for interactive graphics. ggplot is great, but it is static. I am sure that someone can design an editor that will allow people to explore data graphically and then produce static descriptions of the generated plots.

I have never used other statistic tools seriously. Closed source ones I would not use, as my research could not be replicated without a license. From the open source ones, I would not use Weka, because I find clicking around an inferior way of providing input to a program, especially since I would like executions to be scripted. Therefore, my choices are trimmed down to three: R, Octave and SciPy - SciKit. Octave does not include a robust machine learning toolkit. SciPy is more promising, after all it is based on a rather nice programming language, but it does not have ggplot. While waiting for a new statistics language to arrive, I am going to give SciPy a try for my next work.



Published

05 March 2013

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