# Monthly Archives: May 2013

## Rmagic, A Handy Interface Bridging Python and R

May 31, 2013
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Rmagic (http://ipython.org/ipython-doc/dev/config/extensions/rmagic.html) is the ipython extension that utilizes rpy2 in the back-end and provides a convenient interface accessing R from ipython. Compared with the generic use of rpy2, the rmagic extension allows users to exchange objects between ipython and R in a more flexible way and to run a single R function or a block

## How logistic regression work ?

May 31, 2013
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Discussing with a non statistician colleague, it seems that the logistic regression is not intuitive; Some basics questions like : - Why don't use the linear model? - What's logistic function? - How can we compute by hand, step by step t...

## Generating Nice Looking Tree Diagrams in R

May 31, 2013
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This function generates nice looking tree diagrams (see sample) below from tree objects (generated by package tree). This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option)

## Using the rasterVis package for raster plotting (in R)

May 31, 2013
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Here is a post discussing the possibilities of the rasterVis package: http://rpubs.com/Lionel/6374Filed under: R and Stat Tagged: R, raster

## Snowfall

May 31, 2013
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Yesterday I had a short post reminding EViews users that their package (versions 7 or 8) will access all of the cores on a multi-core machine. I've been playing around with parallel processing in R on my desktop machine at work over the last few days. It's something I've been meaning to do...

## The arteries of the world, in Tweets

May 31, 2013
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What happens when you plot billions of geotagged Tweets on a map? You can see the arteries of the world. Here's Europe: According to creator Miguel Rios (Engineering Manager, Data Visualization at Twitter), the dots on this chart represent every geotagged Tweet since 2009. The color represents number of tweets in the region, and the intensity shows where people...

## Are parallel computations worth it ?

May 31, 2013
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Yesterday, Daniel Marcelino published an interesting post on his blog, untitled Parallel Processing: When does it worth ? I was asking myself the same question for a chapter I am currently writing. And I did like his approach, so I tried, on my computer to do the same. I did use three packages to run parallel R codes, >...

## Regression regularization example

May 31, 2013
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Recently I needed a simple example showing when application of regularization in regression is worthwhile. Here is the code I came up with (along with basic application of parallelization of code execution). Assume you have 60 observations and 50 expla...

## accurate ABC: comments by Oliver Ratman [guest post]

May 31, 2013
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Here are comments by Olli following my post: I think we found a general means to obtain accurate ABC in the sense of matching the posterior mean or MAP exactly, and then minimising the KL distance between the true posterior and its ABC approximation subject to this condition. The construction works on an auxiliary probability