Triples, stores, and SPARQL in R

November 27, 2012
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For some time I have been stealing an hour here and there for the rrdf package for R. This package is based on Apache Jena and allows reading and writing of RDF triples, as well as doing local and remote SPARQL querying. BTW, rrdf is not only R pa...

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Creating PDFs and websites with the "knitr" package

November 27, 2012
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Just a fast note: I came across the R-package "knitr" which enables you to generate PDF files by mixing LaTeX and R code in one document. The result looks very nice and is great to create documentations, manuals and so on. I find knitr much easier to u...

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"Dominant" Color Palettes with k-means

November 27, 2012
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"Dominant" Color Palettes with k-means

The idea of deriving color palettes from images has long been an interest of mine. There are places you can do this online, but it’s at least plausible that you might want to identify dominant colors programatically, for a large number of image...

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Exporting data from R into WinBUGS’s “R/S-plus list format”

November 27, 2012
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Exporting data from R into WinBUGS’s “R/S-plus list format”

Users of the world’s favourite Bayesian analysis software WinBUGS will recognise the strange format in which data is supplied inside the GUI, generally in a text file looking something like this: list(x=c(1,2,3,4,5,6),y=c(4,8,2,6,9,9)) This is of course an R (or strictly … Continue reading →

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Fifty Shades of Grey in R

November 27, 2012
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Fifty Shades of Grey in R

My wife went out to her book group tonight and their book of the month was 50 Shades of Grey. Sadly, I could think of is that plotting 50 shades in R would be a neat exercise. require(ggplot2) grey50 <- data.frame( x = rep(1:10, 5), y = rep(1:5, ...

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Data.table rocks! Data manipulation the fast way in R

November 27, 2012
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Data.table rocks! Data manipulation the fast way in R

I really should make it a habit of using data.table. The speed and simplicity of this R package are astonishing. Here is a simple example: I have a data frame showing incremental claims development by line of business and origin year. Now I would like add a column with the cumulative claims position for each line of...

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2012-10 Introducing the ‘selectr’ Package

November 26, 2012
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The selectr package translates a CSS selector into an equivalent XPath expression. This allows the use of CSS selectors to query XML documents using the XML package. Convenience functions are also provided to mimic functionality present in modern web browsers. … Continue reading →

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Applications open for 2013 John M Chambers Statistical Software Award

November 26, 2012
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In 1998, John Chambers won the ACM Software Systems award for the S language, which the ACM heralded as having "forever altered how people analyze, visualize, and manipulate data". The R language is "not unlike S", and John continues pushing the frontiers of statistical computing as a member of the R Core Group. Ang his legacy continues in another...

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Image Manipulation in R, Part 1

November 26, 2012
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Image Manipulation in R, Part 1

So, you know how to load PNG files, access their innards, and plot them as points in a scatter plot. But, is it possible to use R to do some of the awesome things you can do with Mathematica? Well, in this series of posts, I’ll introduce just ...

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is.invasive( )

November 26, 2012
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is.invasive( )

Celebrating that I am contributing to the R-bloggers.com blog aggregator I am going to post a very simple function to check which species (both plants and animals) are considered “invaders” somewhere in the world. Basically the function asks that to … Continue reading →

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Discovering the quality of portfolio decisions

November 26, 2012
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Discovering the quality of portfolio decisions

Performance analysis of an example portfolio. The portfolio We explore a particular portfolio during 2007.  It invests in S&P 500 stocks and starts the year with a value of $10 million.  Initially there are 50 names in the portfolio.  It also ends the year with 50 names but has up to 53 names during the … Continue reading...

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why and how to install monetdb with r on windows

November 26, 2012
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warning: the instructions below are obsolete.  please check this page for the latest version.  <3 anthony whya speed test of three sql queries on sixty-seven million records using my personal computer --# calculate the sum, mean, median, a...

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Minimizing Bias in Observational Studies

November 26, 2012
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Minimizing Bias in Observational Studies

Measuring the effect of a binary treatment on a measured outcome is one of the most common tasks in applied statistics. Examples of these applications abound, like the effect of smoking on health, or the effect of low birth weight on cognitive development. In an ideal world we would like to be able to assign

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Fast Conway’s game of life in R

November 25, 2012
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Fast Conway’s game of life in R

Here I demonstrate a simple way to code Conway's game of life (GoL) in R and to produce the animation above. Cellular automata in R are usually painfully slow if you iterate through all grid cells in an array. A…Read more →

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Mapping Current Average Price Per Sqft for Rentals by Zip in San Fran

November 25, 2012
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Mapping Current Average Price Per Sqft for Rentals by Zip in San Fran

My company, Kwelia, is sitting on mountains of data, so I decided to try my hand at mapping.  I have played around with JGR but it’s just too buggy, at least on my mac, so I went looking for other alternatives and found a good write up here.  I decided on mapping prices per sqft

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The perks (and quirks) of being a referee

November 25, 2012
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The other day I was talking to a friend at work, who was rather annoyed that one of his papers had been rejected by a journal, given the negative comments of the reviewers. This is, of course, part of the game, so you don't really get annoyed just because a paper get rejected. From what I hear, though, I...

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digest 0.6.0

November 25, 2012
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A new version of the digest package (which generates hash function summaries for arbitrary (and possibly nested) R objects using any of the standard md5, sha-1, sha-256, sha-512 or crc32 algorithms) is now on CRAN, and I will push the corresponding ve...

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Yahoo Tickers for DAX,MDAX,SDAX

November 25, 2012
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  In my various R - Tests I'm using usually the Yahoo Dataservice implemented in quantmod suppressWarnings(try(getSymbols(ticker, index.class="POSIXct", from=initDate, to=to,src="yahoo"),silent=TRUE))  If you would like to run ...

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Successive Differences of a Randomly-Generated Timeseries

November 25, 2012
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I was wondering about the null distribution of successive differences of random sequences, and decided to do some numerical experiments. I quickly realized that successive differences equates to taking successively higher-order numerical derivatives, ...

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Hello world!

November 25, 2012
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Hello world!

Welcome to WordPress.com! This is your very first post. Click the Edit link to modify or delete it, or start a new post. If you like, use this post to tell readers why you started this blog and what you plan to do with it. Happy blogging!Filed under: U...

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Modis R: Package tutorial

November 24, 2012
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Modis R: Package tutorial

The MODIS package for R For people who work in GIS in R there has been a bit of challenge in working with data from  Modis. I’ll use an example from my own work on UHI to illustrate. A while back I decided that I wanted to look at albedo data from MODIS.  If you

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Run R Code Within Python On The Fly

November 24, 2012
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Run R Code Within Python On The Fly

Below is an example showing how to run R code within python, which is an extremely attractive feature for hardcore R programmers.

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Simulating weak gravitational lensing

November 24, 2012
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Simulating weak gravitational lensing

In the search for dark matter, I have been having mixed success. It seems that locating DM in single halo skies is a fairly straightforward problem. However, when there are more than one halo, things get quite a bit trickier. As I have advocated many times before, including here and here, simulation can provide deep

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Personal CRAN-repository

November 24, 2012
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Personal CRAN-repository

Offering - the backbone of open source. The image is CC by TenthMusePhotography This is part II of the previous package creation post. I've created my own CRAN repository since I wanted a quick upload. Perhaps in the future I'll post on the main server but right now...

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Secret Santa – unfinished business

November 24, 2012
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Last week I wrote:This is actually a more difficult calculation (or I forgot too much probability). Luckily a bit of brute force comes in handy. To reiterate, in general simulated data shows 0.54 redraws because of the first person etc.colSums(countsto...

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ESSA2013 Conference

November 24, 2012
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ESSA2013 Conference

It has been just announced that during ESSA2013 conference I am planning to organize a special track on "Statistical analysis of simulation models". I hope to get some presentations using GNU R to promote it in social simulation community.It is obvious that GNU R excels in analysis of simulation data. However, very often it can be neatly...

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A Light Touch on RPy2

November 23, 2012
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A Light Touch on RPy2

For a statistical analyst, the first step to start a data analysis project is to import the data into the program and then to screen the descriptive statistics of the data. In python, we can easily do so with pandas package. Tonight, I’d like to add some spice to my python learning experience and do

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R is (Almost) Platform Independent

November 23, 2012
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I write R scripts on both my laptop and desktop, so the main issue I have is making sure that the R scripts are updated on these devices. There are several ways to ensure this happens:Use a version control system (on the cloud), e.g GithubWrite R scrip...

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Shootout 2012 : first PLS regressions

November 23, 2012
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Shootout 2012 : first PLS regressions

It´s time to start developing some regressions in order to find the best math treatment, the best number of terms, the best spectral regions, the best regression method,....This time I´m working with the PLS  package in R, and just to make ...

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