If it's an internal function of R (e.g. from base package), just type the function name, like__ rowMeansfunction (x, na.rm = FALSE, dims = 1L) {    if (is.data.frame(x))         x [Read more...]

Panagiotis Petrou has posted a link to a recent paper of his, which develops a cost-effectiveness analysis of a drug used as a second-line treatment of renal carcinoma. The analysis is based on a Bayesian Markov model. But (from an incredibly self... [Read more...]

Stephen tweets: Quilt Plots: A Simple Tool for the #Visualisation of Large Epidemiological Data buff.ly/1doSx4X— Stephen Rudd (@SAGRudd) January 15, 2014 Quilt plots. Sounds interesting. The link points to a short article in PLoS ONE, containing a table and a figure. Here is Figure 1. If you looked at that ... [Read more...]

In a recent post, I did some analysis of the efficiency of the DVI indicator. That was pretty much all I had to say back then, but that quickly changed. While reading Building Reliable Trading Systems, by Keith Fitschen I stumbled upon an alternative way to visualize entry efficiency – the ... [Read more...]

Although I am sure most of the bloggers that discuss R on R-bloggers are not all that concerned with popularity, I thought it would be interesting to analyze (with R and rCharts, of course) the popularity of these bloggers using Feedly’s API.   After building the chart, I got to ... [Read more...]

After reinventing the wheel a few times, I decided it would be a good idea to keep a list of programming tips or tricks that I find useful, so I started a static page here to keep these tips. It will begin rather haphazardly, but if it grows, I will ... [Read more...]

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I thought it would be helpful to new users of Geomorph and R to discuss some tips and tricks for manipulating morphometric datasets in R. So I am starting a series called "Tips & Tricks". These will be published as I think of them, and assume you h... [Read more...]

Fast-track publishing using knitr is a short series on how I use knitr to speedup publishing in my research. While illustrations (previous post) are optional, tables are not, and this fourth article is therefore devoted to tables. Tables through knitr is probably one of the most powerful fast-track publishing tools, ... [Read more...]

As I have described before, Linear Discriminant Analysis (LDA) can be seen from two different angles. The first classify a given sample of predictors to the class with highest posterior probability . It minimizes the total probability of misclassification. To compute it uses Bayes’ rule and assume that follows a Gaussian ... [Read more...]

Abstract R code is provided in aide of laboratory demonstration of cabelling. Introduction Setting up a cabelling experiment requires creating two watermasses of equal density, and if only S and T can be measured, that means calculating densities. Using a TS diagram and graphical interpolation is one approach to that ... [Read more...]

Introduction Butterworth filters with order other than 1 have an overshoot phenomenon that can be problematic in some cases. For example, if smoothing is used on an estimate of kinetic energy, overshoots might yield negative values that are nonphysical. This post simply illustrates this with made-up data that the reader can ... [Read more...]

Introduction In Oceanography it can be useful to use colour to display z values along an (x,y) trajectory. For example, CTD data might be displayed in this way, with x being distance along track, y being depth, and z being temperature. This post shows how one might do this. ... [Read more...]

I was recently made aware of this great article by Alexis C. Madrigal, senior editor at the Atlantic. Although the underlying analysis he performs is relatively straightforward, it is more the fact that he actually thought of doing it…and went through with it! It is a relatively long read ... [Read more...]

Our crack-shot R trainer Luba Gloukhov generated a spirited (pun intended!) discussion from her post K-means Clustering 86 Single Malt Scotch Whiskies, with mentions of her analysis at FlowingData and Reddit amongst others. Other bloggers took a look at the data too, notably Christopher Ingraham who created this beautiful infographic of ... [Read more...]

I am strangely attracted to you (Cole Porter) Imagine a linear grid that extends to the left and right. The grid consists of cells that may be only one of these two states: On or Off. At each time step, the next state of a cell is computed as a ... [Read more...]

A colleague had a question about sampling design and we didn’t find a good answer … so, if you like to solve riddles, you might like that one: We want to distribute n=3 plant species across k=12 x m=12 grid cells, in a way that no individual has another individual ... [Read more...]

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As I said in my last post, rgdal lacks some of the features of GDAL, including the ability to subset columns and rows the source layer, and I demonstrated a workaround. The workaround relied upon the RPostgreSQL package, and this raises a question: Is it possible to transfer geographic data ... [Read more...]