Monthly Archives: June 2013

Grid Search for Free Parameters with Parallel Computing

June 1, 2013
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Grid Search for Free Parameters with Parallel Computing

In my previous post (http://statcompute.wordpress.com/2013/05/25/test-drive-of-parallel-computing-with-r) on 05/25/2013, I’ve demonstrated the power of parallel computing with various R packages. However, in the real world, it is not straight-forward to utilize these powerful tools in our day-by-day computing tasks without carefully formulate the problem. In the example below, I am going to show how to use the

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Mapping a Revolution

June 1, 2013
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Mapping a Revolution

Twitter has become an important communications tool for political protests. While mass media are often censored during large-scale political protests, Social Media channels remain relatively open and can be used to tell the world what is happening and to mobilize support all over the world. From an analytic perspective tweets with geo information are

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Loading Historical Stock Data

June 1, 2013
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Loading Historical Stock Data

Historical Stock Data is critical for testing your investment strategies. I illustrated all my back-test examples with getSymbols function from quantmod package. For example, following is a back-test comparison for a few portfolio allocation methods: The getSymbols function, from quantmod package, downloads historical stock prices from Yahoo Fiance. I often get questions about alternative ways

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Tweetanalytics – Interactively analyzing tweets from accounts of 5 universities

June 1, 2013
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Tweetanalytics – Interactively analyzing tweets from accounts of 5 universities

This is an attempt at learning and interactively displaying few results using twitter data using text mining. Interactivity is implemented using RStudio's shiny server. Their documentation of demo scripts came in very handy. As a non-user of twitter, I...

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A map of the world by tweets

June 1, 2013
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A map of the world by tweets

With geo-tagging enabled, tweets include information on the location of the user when the tweet was sent. Miguel Rios (@miguelrios) has plotted locations of billions of tweets to create maps of the world. This is pretty amazing stuff – a world map rendered just from twitter posts! Maps are created using every tweet from 2009

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Flotsam 12: early June linkathon

June 1, 2013
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A list of interesting R/Stats quickies to keep the mind distracted: A long draft Advanced Data Analysis from an Elementary Point of View by Cosma Shalizi, in which he uses R to drive home the message. Not your average elementary point of view. Good notes by Frank Davenport on starting using R with data from

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Fylopic, an R wrapper to Phylopic

June 1, 2013
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Fylopic, an R wrapper to Phylopic

What is PhyloPic? PhyloPic is an awesome new service - I'll let the creator, Mike Keesey, explain what it is (paraphrasing here): PhyloPic stores silhouette images of organisms, and each image is associated with taxonomic names, and stores the taxonomy of all taxa, allowing searching by taxonomic names. Anyone can submit silhouettes to PhyloPic. What is a silhouette? It's like...

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Fylopic, an R wrapper to Phylopic

June 1, 2013
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Fylopic, an R wrapper to Phylopic

What is PhyloPic? PhyloPic is an awesome new service - I'll let the creator, Mike Keesey, explain what it is (paraphrasing here): PhyloPic stores silhouette images of organisms, and each image is associated with taxonomic names, and stores the taxonomy of all taxa, allowing searching by taxonomic names. Anyone can submit silhouettes to PhyloPic. What is a silhouette? It's like...

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