2105 search results for "Twitter"

Teach Yourself How to Create Functions in R

February 1, 2011
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Teach Yourself How to Create Functions in R

As you can tell from my previous posts, I am diving in head first into learning how to program (and simplify) my analytical life using R.  I have always learned by example and have never really prospered from the “learn from scratch” school of thought.  As I follow along with some other fellow R programmers,

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Tricks to manage memory in an R session

January 31, 2011
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Unless you're using an out-of-memory solution to manage large data objects (such as the RevoScaleR package in Revolution R Enterprise), then R always allocates memory for every object in your working session. If you're working with many objects (or even just a few large objects) then you'll need to take care to manage R's memory usage to avoid the...

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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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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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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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ABC model choice not to be trusted [2]

January 27, 2011
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ABC model choice not to be trusted [2]

As we were completing our arXiv summary about ABC model choice, we were helpfully pointed to a recent CRiSM tech. report by X. Didelot, R. Everitt, A. Johansen and D. Lawson on  Likelihood-free estimation of model evidence. This paper is quite related to our study of the performances of the ABC approximation to the Bayes

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Building a Better Word Cloud

January 27, 2011
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Building a Better Word Cloud

A few weeks ago I attended the NYC Data Visualization and Infographics meetup, which included a talk by Junk Charts blogger Kaiser Fung. Given the topic of his blog, I was a bit shocked that the central theme of his talk was comparing good and bad word clouds. He even stated that the

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Speed up your R code

January 26, 2011
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Speed up your R code

This short post is to share an R tip Pierre recently gave me. When you need to store values sequentially (typically inside a loop), it’s more far efficient to create the whole vector (or matrix) and to fill it, rather than to concatenate the values to your current vector (or matrix). In terms of allocation

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ABC model choice not to be trusted

January 26, 2011
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ABC model choice not to be trusted

This may sound like a paradoxical title given my recent production in this area of ABC approximations, especially after the disputes with Alan Templeton, but I have come to the conclusion that ABC approximations to the Bayes factor are not to be trusted. When working one afternoon in Park City with Jean-Michel and Natesh Pillai

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sab-R-metrics: Intermediate Scatter Plots

January 25, 2011
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sab-R-metrics: Intermediate Scatter Plots

First off, I'll say it's been a whirlwind of a past few days. Thanks to David Smith at the Revolutions Blog for his kind words about the sab-R-metrics series and link back this way. Add in Ed Kupfer's posts at the APBRmetrics board, Harry Pavlidis at THT, Dave Allen at Fangraphs...

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