2645 search results for "gis"

Choropleth tutorial and regression coefficient plots

February 21, 2011
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Choropleth tutorial and regression coefficient plots

About two weeks ago, I gave short talk at Duke, wherein I presented a brief tutorial on creating choropleth maps in R using ggplot2. Since the code is already written, and the data and shapefiles already hosted online, I thought I would share the tutorial more widely. A .ZIP file containing all the files necessary … Continue reading →

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Tracking the Frequency of Twitter Hashtags with R

February 21, 2011
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Tracking the Frequency of Twitter Hashtags with R

 I’ve posted three examples of Twitter hashtags datasets in the last week: one on China, one on Iran, and one on Algeria.  In order to build these datasets, I needed to obtain older tweets; this is slightly more difficult than … Continue reading →

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Dataset: Tweets from the Chinese Protests #cn220

February 20, 2011
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Dataset: Tweets from the Chinese Protests #cn220

  Earlier this week, I posted a ~100k tweet dataset on the #25bahman protests in Iran.  The corresponding figure of frequencies showed a strong presence on Twitter, with over 500 tweets per 5 minute period at peak.  You can download the … Continue reading →

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Aligning labels in circular igraph layouts

February 18, 2011
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Aligning labels in circular igraph layouts

The folks at IPE at UNC have produced this nice animated gif of some network data on increasing financial integration in the run-up to the 2008 crisis. They used a small trick I pointed to a while ago (just using a pipe, nothing fancy) that lets you generate the gif from within R without tediously

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Aligning labels in circular igraph layouts

February 18, 2011
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Aligning labels in circular igraph layouts

The folks at IPE at UNC have produced this nice animated gif of some network data on increasing financial integration in the run-up to the 2008 crisis. They used a small trick I pointed to a while ago (just using a pipe, nothing fancy) that lets you ...

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Stata or R – How to create dynamic variables in R?

February 16, 2011
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As we dig deeper into Stata or R debate, a few questions have come up.Question 1: One of the things Stata does well is the way it constructs new variables (see example below). How to do this in R? We can rewrite it as-is using for loops in R...

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Stata or R – How to create dynamic variables in R?

February 16, 2011
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As we dig deeper into Stata or R debate, a few questions have come up.Question 1: One of the things Stata does well is the way it constructs new variables (see example below). How to do this in R? We can rewrite it as-is using for loops in R...

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Pre-processing text: R/tm vs. python/NLTK

February 16, 2011
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Pre-processing text: R/tm vs. python/NLTK

  Let’s say that you want to take a set of documents and apply a computational linguistic technique.  If your method is based on the bag-of-words model, you probably need to pre-process these documents first by segmenting, tokenizing, stripping, stopwording, and … Continue reading →

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ABC in London

February 15, 2011
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ABC in London

After the very exciting and I think quite successful ABC in Paris meeting two years ago, Michael Stumpf from Imperial College London suggested a second edition in London along the same lines. Michael kindly associated me with the planning of this meeting. It is (logically) called ABC in London (or ABCiL) and will take place

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R 2.12.2 scheduled for February 25

February 15, 2011
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The next release of R is scheduled for release February 25, and R 2.12.2 will likely be the final bug-fix release of the 2.12 series before R 2.13 is released in April. According to the NEWS file in the latest daily build, 2.12.2 will improve complex-arithmetic support on some rare platforms that don't support complex types in C99, and...

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