Monthly Archives: January 2011

Good riddance to Excel pivot tables

January 30, 2011
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Good riddance to Excel pivot tables

Excel pivot tables have been how I have reorganized data...up until now. These are just a couple of examples why R is superior to Excel for reorganizing data:################ Good riddance to pivot tables ############library(reshape2)library(plyr)&nbsp...

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ABC model choice not to be trusted [3]

January 30, 2011
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ABC model choice not to be trusted [3]

On Friday, I received a nice but embarrassing email from Xavier Didelot. He indeed reminded me that I attended the talk he gave at the model choice workshop in Warwick last May, as, unfortunately but rather unsurprisingly giving my short span memory!, I had forgotten about it! Looking at the slides he joined to his

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Code: parsing Slovenian exchange rate data

January 30, 2011
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Some time ago I found myself in need of daily exchange rates for the Slovenian Tolar (though I can’t now remember why). Unfortunately, I wasn’t able to find the data in a readily usable format at the Bank of Slovenia … Continue reading →

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Data Mining with WEKA

January 30, 2011
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There are a number of good open source projects for statistics and data mining, for example the software WEKA developed at the University of Waikato. The description on their website states that: Weka is a collection of machine learning algorithms for data mining tasks. The algorithms can either be applied directly to a dataset or

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Statistical Computing and Graphics Newsletter

January 30, 2011
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Statistical Computing and Graphics Newsletter

The new issue (Vol. 21, No. 2) is out now. Featured articles are: barNest: Illustrating nested summary measures by Jim Lemon and Ofir Levy You say “graph invariant,” I say “test statistic” by Carey E. Priebe, Glen A. Coppersmith and Andrey Rukhin Computation in Large-Scale Scientific and Internet Data Applications is a Focus of MMDS 2010

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Tab completion

January 30, 2011
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Let's say your hands are aching from too much typing in of variables. What to do? Get a keyboard tray and learn proper ergonomics, of course.But what if you just want to reduce the amount of typing in of variables you do for reasons of laziness...err...

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R exam

January 30, 2011
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R exam

I spent most of my Saturday perusing R codes to check the answers written by my students to the R exam I gave two weeks ago… The outcome is mostly poor, even though some managed to solve a fair part of the long problem. Except for the few hopeless cases who visibly never wrote a

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Boxplots and Beyond – Part I

Boxplots and Beyond – Part I

Boxplots are a simple and reasonably popular way of summarizing the range of variation of a real-valued variable across different subsets of data.  Typical examples might include diastolic blood pressure across a group of patients, broken dow...

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R programming books (updated)

January 28, 2011
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R programming books (updated)

In a recent post, I asked for suggestions for introductory R computing books. In particular, I was looking for books that: Assume no prior knowledge of programming. Assume very little knowledge of statistics. For example, no regression. Are cheap, since they are for undergraduate students. Some of my cons aren’t really downsides as such. Rather,

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Converting strsplit() output to a data.frame

January 28, 2011
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R has a nice set of utilities to work with strings. Function paste is surely one among these. It can be used to "glue" several strings with optional separator. The following example shows how paste can be used to create a new variable in a dataset:dat (dat$z Today I was in a situation where I only had column...

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