## Fitting an ellipse to point data

September 30, 2012
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Some time ago I wrote an R function to fit an ellipse to point data, using an algorithm developed by Radim Halíř and Jan Flusser1 in Matlab, and posted it to the r-help list. The implementation was a bit hacky, returning odd results for some data. A couple of days ago, an...

## An R-based Research Notebook – Test

September 30, 2012
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The following are from Tom Torsney-Weir’s blog (here’s the repo). Simple MathJax and R example A more complex example with caching <!--begin.rcode test2,cache=TRUE x.vals <- runif(10) y.vals Another plotting example using ggplot <!--begin.rcode test3,cache=TRUE, message=FALSE library(ggplot2) c Example using googleVis <!--begin.rcode test4,cache=TRUE, message=FALSE, results='asis' suppressPackageStartupMessages(library(googleVis)) ## Table with embedded links PopTable

## Working with Bipartite/Affiliation Network Data in R

September 30, 2012
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Data can often be usefully conceptualized in terms affiliations between people (or other key data entities). It might be useful analyze common group membership, common purchasing decisions, or common patterns of behavior. This post introduces bipartite/affiliation network data and provides … Continue reading →

## Football, an ordinal model

September 30, 2012
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On September 19th, flo2speak remarked under a post that his/her experience is that ordinal models had better performance. That seems reason enough to try, so there we are. In examining this type of model it is found that more complex models can be...

## Plot R Data With googleVis

September 30, 2012
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Here is a little code snippet that shows how to do two things Use the Google Maps API to resolve place names into lat-long coordinate pairs. Plot R dataframes that contain lat-long data (for example from #1) onto Google Maps for quick visualization using the googleVis package.  The embedded map looks a little wonky here but it looks...

## Quantifying student feedback using Org mode and R

September 30, 2012
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As the term has progressed, my LSM2241 lectures are getting more consistent. I’m aiming to use 45 slides for what is officially a two hour lecture, although in reality it lasts about 90 minutes. We take a break at about 50 … Continue reading →

September 29, 2012
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I got very excited on making a network diagram of my Facebook network using Ghefi (https://gephi.org/) and submitted my first assignment for the Social Network Analysis course on https://www.coursera.org/. It's middle of the night, so I will ...

## Padding integers for use in filenames

September 29, 2012
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If you’ve ever written code that generates a whole whack of files, you may have came across the following problem when processing them. Using a naming convention wherein files are numbered will  gum up any ordering which is based on string sorting (ls, for example). What you end up with is something like this: Which

## Merging Dataframes by Partly Matching String

September 29, 2012
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The latest posting by Tony Hirst sparked my attention because I was thinking about a very similar issue recently.I was also fiddling around with agrep and adist until I realised that for this very issue matching of substrings is not as important as matching multiple words.. With this different approach I quite easily matched all but 3...

## Weekend Reading – Gold in October

September 28, 2012
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I recently came across the “An early Halloween for gold traders” article by Mark Hulbert. I have discussed this type of seasonality analysis in my presentation at R/Finance this year. It is very easy to run the seasonality analysis using the Systematic Investor Toolbox. This confirms that October have been historically bad for Gold, but

## Browse the in-development R sources at GitHub

September 28, 2012
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As an open-source project, the R source code has always been available to download from the R-project website. You can find source code for the latest released version here, and for the changing-daily new version in progress (R-devel) here. But if you don't have the R sources handy, and just want to check on the contents of a file...

## Second Milano R net meeting

September 28, 2012
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Second Milano R net meeting took place on September, 27. More than thirty R users joining both the presentations session and the open bar. If you attended the meeting, please leave a comment in the page of the meeting. You … Continue reading →

## Photos of the second Milano R net meeting

September 28, 2012
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Photos of the second Milano R net meeting Milano; September 27, 2012

## Optimal seriation for your matrices

September 28, 2012
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In our previous post, we used a quick-and-dirty method for ordering the axes on our heatmap. It has been pointed out to me that There is a Package for That (which is my nominee for a new slogan for R — not that it needs a slogan). seriation offe...

## Presentations of the second Milano R net meeting

September 28, 2012
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Welcome presentation Andrea Spanò, Partner at Quantide (download PDF, 3.0 MB) Introduction to the next Italian BioR event at PTP Andrea Pedretti, Parco Tecnologico Padano (download PDF, 0.2 MB) Applications of technical risk assessment in Food Industry by R Carlo … Continue reading →

## Reading and Text Mining a PDF-File in R

September 27, 2012
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I just added this R-script that reads a PDF-file to R and does some text mining with it to my Github repo..

## 3-D animation of the changing Antarctic ice sheet

September 27, 2012
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Last month we shared an visualization showing the changing extent of Arctic sea-ice. This visualization by the multinational Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) switches the view to the Southern pole and takes the visualization to a whole new level, by animating it in 3-D: The amount of sea ice in the Southern Ocean surrounding...

## Histogram + Density Plot Combo in R

September 27, 2012
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Plotting a histogram using hist from the graphics package is pretty straightforward, but what if you want to view the density plot on top of the histogram? This combination of graphics can help us compare the distributions of groups.Let's use...

## Set package repositories at startup

September 27, 2012
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The below code shows how to configure the 'repos' option in R such that install.packages() etc will locate the packages without having to explicitly specify the repository.  Just add it to the .Rprofile file in your home directory (iff missing, create it). For more details, see help("Startup").local({ repos # http://cran.r-project.org/ # For a list of CRAN...

## The simplest Species Distribution Model in OpenBUGS & R

September 27, 2012
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This post demonstrates the simplest Species Distribution Model based on logistic regression for presence/absence data. I heavily simplified the example from Kéry (2010): Introduction to WinBUGS for Ecologists, Chapter 20.Read more →

## ROracle support for TimesTen In-Memory Database

September 27, 2012
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Today's guest post comes from Jason Feldhaus, a Consulting Member of Technical Staff in the TimesTen Database organization at Oracle.  He shares with us a sample session using ROracle with the TimesTen In-Memory database.  Beginning in ve...

## Using R in Political Controversies: Unemployment Reduction Prowess Under Bush versus Obama Years

September 27, 2012
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Editor’s note: R-bloggers does not take a political side. Since this is an important topic, this post has the comments turned on. Also, If you wish to write a reply post (which includes an R context), you are welcome to contact me to have it published. This post was written by Prof. H. D. Vinod. Fordham University, New York.

## Continuous dispersal on a discrete lattice

September 27, 2012
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Dispersal is a key process in many domains, and particularly in ecology. Individuals move in space, and this movement can be modelled as a random process following some kernel. The dispersal kernel is simply a probability distribution describing the distance travelled in a given time frame. Since space is continuous, it is natural to use

## Bounding sums of random variables, part 1

September 27, 2012
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$\Delta$

For the last course MAT8886 of this (long) winter session, on copulas (and extremes), we will discuss risk aggregation. The course will be mainly on the problem of bounding  the distribution (or some risk measure, say the Value-at-Risk) for two random variables with given marginal distribution. For instance, we have two Gaussian risks. What could be be worst-case scenario...

## Simplest possible heatmap with ggplot2

September 27, 2012
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Featuring the lovely “spectral” palette from Colorbrewer. This really just serves as a reminder of how to do four things I frequently want to do: Make a heatmap of some kind of matrix, often a square correlation matrix Reorder a factor vari...

## Calling Minimum Correlation Algorithm from Excel using RExcel & VBA

September 26, 2012
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I want to show the example of calling the Minimum Correlation Algorithm from Excel. I will use RExcel to connect R and Excel and will create a small VBA cell array function to communicate between Excel and R. I have previously discussed the concept of connecting R and Excel in the “Calling Systematic Investor Toolbox

## eeptools 0.1 Available on CRAN Now!

September 26, 2012
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eeptools 0.1 is available now on CRAN! You can install it by simply typing:install.packages('eeptools')in your R console now. The package allows users to play with a number of built in datasets for folks in education beginning to learn R, custom themes...

## structure and uncertainty, Bristol, Sept. 26

September 26, 2012
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Another day full of interesting and challenging—in the sense they generated new questions for me—talks at the SuSTain workshop. After another (dry and fast) run around the Downs; Leo Held started the talks with one of my favourite topics, namely the theory of g-priors in generalized linear models. He did bring a new perspective on