Monthly Archives: September 2013

Visualizing optimization process

September 8, 2013
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One of the approaches to graph drawing is application of so called force-directed algorithms. In its simplest form the idea is to layout the nodes on plane so that all edges in the graph have approximately equal length. This problem has very intuitive ...

Linear regression from a contingency table

September 7, 2013
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This morning, Benoit sent me an email, about an exercise he found in an econometric textbook, about linear regression. Consider the following dataset, Here, variable X denotes the income, and Y the expenses. The goal was to fit a linear regression (actually, in the email, it was mentioned that we should try to fit an heteroscedastic model, but let...

Vectors, Looping, and Performance

September 7, 2013
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Vectors are at the heart of R and represent a true convenience. Moreover, vectors are essential for good performance especially when your are working with lots of data. We’ll explore these concepts in this posting. As a motivational example let’s generate a sequence of data from -3 to 3. We’ll also use each point as

Vectors, Looping, and Performance

September 7, 2013
By

Vectors are at the heart of R and represent a true convenience. Moreover, vectors are essential for good performance especially when your are working with lots of data. We’ll explore these concepts in this posting. As a motivational example let’s generate a sequence of data from -3 to 3. We’ll also use each point as

A bit of benchmarking with string distances

September 7, 2013
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After my last post about the stringdist package, Zachary Mayer pointed out to me that the implementation of the Levenshtein and Jaro-Winkler distances implemented in the RecordLinkage package are about two-three times faster. His benchmark compares randomly generated character strings … Continue reading →

First post, and its a doozy!

September 7, 2013
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Well, not really a doozy.  Just something nice and slow to get me going. So, seeing as I intend to post stuff about R along with the other things, I thought it best to understand how all those great R bloggers embed the highlighted R code into their WordPress blogs.  As it turns out, I

Fearsome Engines, Part 1

September 7, 2013
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Back in June I discovered pqR, Radford Neal’s fork of R designed to improve performance. Then in July, I heard about Tibco’s TERR, a C++ rewrite of the R engine suitable for the enterprise. At this point it dawned on me that R might end up like SQL, with many different implementations of a common

September 7, 2013
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R packages to provide more interactive and richer user experience: knitr, rCharts, slidify, shiny and OpenCPU.

Probability of Avoiding a Run-off in the NYC 2013 Democratic Primary Election

September 6, 2013
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The New York City mayoral Democratic primary election is taking place this coming Tuesday (Sep. 10th) and there are several candidates in the running. Bill de Blasio is the front runner and is expected to win. However, there is a catch. Even if he takes the plurality of the vote he may not actually win.

Mimic Bigger is not Better Post by Scannel & Kurz

September 6, 2013
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The following Github repo has the R code I put together that allows us to follow along and modify the great idea from Scannel & Kurz on app growth and it’s impact on yield. https://github.com/Btibert3/sk-delta-apps-yield/blob/master/README.md Take a look at the repo and feel free to clone it if you want to learn R or add