2145 search results for "MAP"

Do we need to deal with ‘big data’ in R?

November 22, 2011
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Do we need to deal with ‘big data’ in R?

David Smith at the Revolutions blog posted a nice presentation on “big data” (oh, how I dislike that term). It is a nice piece of work and the Revolution guys manage to process a large amount of records, starting with … Continue reading →

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Sermon Sentiment Analysis

November 22, 2011
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Sermon Sentiment Analysis

Matt Chandler vs. Mark Driscoll I came across an interesting API from Viral Heat which is capable of “Sentiment Analysis.” This analysis is designed to capture the sentiment of a statement by ranking it on a scale from -1 to 1. For instance, a chipper sentence like “The smell of roses makes me giddy!” is

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Functional and Parallel time series cross-validation

November 21, 2011
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Functional and Parallel time series cross-validation

Rob Hyndman has a great post on his blog with example on how to cross-validate a time series model.  The basic concept is simple:  You start with a minimum number of observations (k), and fit a model (e.g. an arima model) to those observation...

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htmlToText(): Extracting Text from HTML via XPath

November 18, 2011
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htmlToText(): Extracting Text from HTML via XPath

Converting HTML to plain text usually involves stripping out the HTML tags whilst preserving the most basic of formatting. I wrote a function to do this which works as follows (code can be found on github): The above uses an XPath approach to achieve it’s goal. Another approach would be to use a regular expression. These

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Black-Litterman Model

November 15, 2011
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Black-Litterman Model

The Black-Litterman Model was created by Fisher Black and Robert Litterman in 1992 to resolve shortcomings of traditional Markovitz mean-variance asset allocation model. It addresses following two items: Lack of diversification of portfolios on the mean-variance efficient frontier. Instability of portfolios on the mean-variance efficient frontier: small changes in the input assumptions often lead to

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First attempt at Chess Data Mining

November 15, 2011
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First attempt at Chess Data Mining

Once you become addicted to chess game analysis, it becomes very easy to swamp yourselves with questions regarding different aspects of the game. Testing out different hypothesis like preference of mobility versus positional advantage requires a bit of manual chess game mining, which could potentially be analyzed using R. With the help of websites like

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Announcing Revolution R Enterprise 5.0

November 15, 2011
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We're proud to announce the latest update to the enhanced, commercial-grade distribution of R, Revolution R Enterprise 5.0. With each new release, Revolution R Enterprise adds more capabilities to open-source R, to make R users more productive, to improve performance of R programs, to support Big Data analytics, and to provide servers and APIs for enterprise deployment. New features...

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Home Runs heating up?

November 12, 2011
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Home Runs heating up?

My intuition tells me that objects traveling through the air would meet more resistance when there is more moisture in the air. It turns out that my intuition is wrong. It still doesn’t make sense to me but apparently humid … Continue reading →

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Visualizing Likert Items

November 11, 2011
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Visualizing Likert Items

I have become quite a big fan of graphics that combine the features of traditional figures (e.g. bar charts, histograms, etc.) with tables. That is, the combination of numerical results with a visual representation has been quite useful for exploring descriptive statistics. I have wrapped two of my favorites (build around ggplot2) and included them as part

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A chart for marathoners

November 11, 2011
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A chart for marathoners

Here's a cool application of calendar heat maps: runner Andy used R to catalogue his daily running mileage over the last 2+ years: There are lots of ways to chart data like this (a simple time-series chart, for example), but sometimes looking at data in new ways offers fresh perspectives. For example, Andy notes: "Apparently I missed running on...

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