Articles by csgillespie

Simon Urbanek – R Graphics: supercharged

August 18, 2011 | csgillespie

New features: rasterImage() (R2.11) bitmap raster drawing; have maps as data backdrops. Polygons with holes: polypath() -(R2.12) At present there is no way to tell when to actually show the plot. For example: plot(x); lines(x). Should we display the plot after plot or after lines Solution dev.... [Read more...]

Kaleidoscope IIIb (useR! 2011)

August 18, 2011 | csgillespie

O. Mersmann - The microbenchmark package Slides and code (link). SURGEON GENERAL’s WARNING: Microbenchmarks can lead to a distorted view of reality and massive loss of productivity For a higher-order benchmarking package check out the rbenchmark package on R (suggestion from the speaker). Why do we need micro-benchmarking? A ... [Read more...]

Big data (useR! 2011)

August 18, 2011 | csgillespie

Unfortunatley, I missed the first and last talks. My notes from a session on Thursday morning J. Demmler – Challenges of working with a large database of routinely collected health data The SAIL data bank holds over 1.9 billion (anonymous) entries. To use the data for research, they need to ensure that ... [Read more...]

Programming (useR! 2011)

August 17, 2011 | csgillespie

Ray Brownrigg – Tips and Tricks for young R programmers Problem: Calculate the distribution function of a bivariate Kolomogorov Smirnoff statistic. Essentially three loops. Basic exhaustive search is O(N^3). Fortran gives a single order of magnitude speed-up. Restructuring in R using a single loop is an order faster than fortran. ... [Read more...]

Kaleidoscope IIb (useR! 2011)

August 17, 2011 | csgillespie

L Collingwood – RTextTools RTextTools. A machine learning library for automated text classification. This package builds on previous packages such as tm and random forests. Use case: undergrad labels congressional bills but then quits. Using the previously labelled data, automatically classify the remaining documents. The speaker gave a nice overview of ... [Read more...]

Ulrike Gromping – Design of Experiments in R

August 16, 2011 | csgillespie

Example: Car seat occupation: Algorithm must decide whether airbag opens: Must open for adult but not for small child or if the seat if empty a few others I missed. Key questions are: What type of design: 32 run regular fractional factorial Response measurement – depends on dummy position, so repeat for 3 ... [Read more...]

High Performance Computing

August 16, 2011 | csgillespie

Wilem Ligtenberg – GPU computing and R Why GPU computing – theoretical GFLOPs for a GPU is three times greater than a CPU. Use GPUs for same instruction multiple data problems (SIMD). Initially GPUs were developed for texture problems. For example, a wall smashed into lots of pieces. Each core handled a ... [Read more...]

Kaleidoscope Ic (useR! 2011)

August 16, 2011 | csgillespie

These are my rough notes on the Kaleidoscope Ic session. David Smith – The R Ecosystem (useR! 2011) David Smith works for Revolution Analytics. Quick overview of the R project – useR, r-journal, and r-forge. Social media starting to play a part in R – Google+, twitter, stackoverflow, and the traditional R mailing list. ... [Read more...]

Brian Ripley – The R Development Process (useR! 2011)

August 16, 2011 | csgillespie

There are my notes on the User2011 invited talk. Brian Ripley has been a member of R core since 1998 The R Development Process – A insideR’s view R Timeline: JCGS paper submitted in 1995. 1997: CRAN(Mar), Core team(Aug), CVS (Sept) R 1.0.0 Feb 2000 – 2.8MB. Many people don’t take 0.X.X ... [Read more...]

Character occurrence in passwords

June 16, 2011 | csgillespie

As everyone knows, it seems that Sony is taking a bit of a battering from hackers.  Thanks to Sony, numerous account and password details are now circulating on the internet. Recently, Troy Hunt carried out a brief analysis of the password structure. Here is a summary of his post: There ... [Read more...]

Makefiles and Sweave

May 12, 2011 | csgillespie

A Makefile is a simple text file that controls compilation of a target file. The key benefit of using Makefile is that it uses file time stamps to determine if a particular action is needed. In this post we discuss how to use a simple Makefile that compiles a tex ... [Read more...]

“An R package” or “A R package”

March 26, 2011 | csgillespie

I’m currently writing some lecture notes on R and I used the phrase “a R package” without thinking. Since the word following the article “a” was a consonant, I automatically went for “a” instead of “an”. The problem is that “R” sounds likes a vowel, so “a R package” ... [Read more...]

Graphical Display of R Package Dependencies

March 23, 2011 | csgillespie

In some work that I am currently involved in, we have to decide which GUI engine we should use. As an obvious starter, we decided to have a look at what other people are using in their packages. While cran helpfully displays all the R packages that are available, it ... [Read more...]

R programming books (updated)

January 28, 2011 | csgillespie

In a recent post, I asked for suggestions for introductory R computing books. In particular, I was looking for books that: Assume no prior knowledge of programming. Assume very little knowledge of statistics. For example, no regression. Are cheap, since they are for undergraduate students. Some of my cons aren’... [Read more...]

CPU and GPU trends over time

January 25, 2011 | csgillespie

GPUs seem to be all the rage these days. At the last Bayesian Valencia meeting, Chris Holmes gave a nice talk on how GPUs could be leveraged for statistical computing. Recently Christian Robert arXived a paper with parallel computing firmly in mind. In two weeks time I’m giving an ...
[Read more...]

Parsing and plotting time series data

January 15, 2011 | csgillespie

This morning I came across a post which discusses the differences between scala, ruby and python when trying to analyse time series data. Essentially, there is a text file consisting of times in the format HH:MM and we want to get an idea of its distribution. Tom discusses how ...
[Read more...]

Statistical podcast: Random and Pseudorandom

January 14, 2011 | csgillespie

This morning when I downloaded the latest version of In our time, I was pleased to see that this weeks topic was “Random and Peudorandom.” If you’re not familiar with “In our time”, then I can I definitely recommend the series. Each week three academics and Melvyn Bragg discuss ...
[Read more...]
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