In mixture experiments there is a constraint that the variables are the proportions of components that are mixed together with the consequence that these proportions sum to one. When fitting regression models to data from mixture experiments we may be interested in reprenting the fitted model with a surface plot. Read the rest of this entry »
Surfaces in ternary plots
February 1st, 2012Cricket All Round Performances
September 19th, 2011In cricket a player who can perform well with both the bat and bowl is a great asset for any team and across the history of international cricket there have been a number of cricketers that hall into this bracket. Read the rest of this entry »
Colours in R
September 19th, 2011There is a handy webpage which provides a chart of colours available in R. The chart is also available in pdf from the webpage.
Getting rid of white space at the beginning and end of a string
July 28th, 2011There are situations where we are working with character strings extracted from various sources and it can be annoying when there is white space at the beginning and/or end of the strings. This whitespace can cause problems when attemping to sort, subset or various other common operations. Read the rest of this entry »
R.NET
July 4th, 2011The R.NET project provides a mechanism for communicating with R from a .NET application. This appears to be a promising way to create simple interfaces to some of the functionality of R. Read the rest of this entry »
Generalized Linear Models – Poisson Regression
June 26th, 2011The Generalized Linear Model (GLM) allows us to model responses with distributions other than the Normal distribution, which is one of the assumptions underlying linear regression as used in many cases. When data is counts of events (or items) then a discrete distribution is more appropriate is usually more appropriate than approximating with a continuous distribution, especially as our counts should be bounded below at zero. Negative counts do not make sense. Read the rest of this entry »
Handling Errors Gracefully
May 27th, 2011In R functions sometimes produces warnings or errors. In the case of errors execution of a function or a series of commands can get halted when an error occurs, which can in some cases be frustrating especially if we want to continue our calculations. Read the rest of this entry »
RStudio
April 29th, 2011R Matrix Operations
March 27th, 2011R can be used to perform various matrix calculations. This include functions for creating matrices (matrix), addition (+), multiplication (%*%) and inversion (solve). Read the rest of this entry »
R Package Automated Download
March 6th, 2011There are situations where we might want to run R on a standalone machine so need to download a (potentially) large number of packages to install on this system. Rather than having to through the pain of searching through CRAN to find the packages and all the dependencies and manually download, it would be nice to be able grab all available packages in one go and then set them up as a local repository. Read the rest of this entry »
