Monthly Archives: February 2014

R User Groups Update

February 27, 2014
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R User Groups Update

by Joseph Rickert After an end-of-year slow down in R user group acrtivity that lasted into mid January, the Revolution Analytics’ Community Calendar indicates that R user groups worldwide are back in full swing with 48 events listed in the short month of February. And, while the total number of active user groups has not grown from this time...

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Example 2014.3: Allow different variances by group

February 27, 2014
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Example 2014.3: Allow different variances by group

One common violation of the assumptions needed for linear regression is heterscedasticity by group membership. Both SAS and R can easily accommodate this setting. Our data today comes from a real example of vitamin D supplementation of milk. Four sup...

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The tf-idf-Statistic For Keyword Extraction

February 27, 2014
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The tf-idf-Statistic For Keyword Extraction

The tf-idf-statistic (“term frequency – inverse document frequency”) is a common tool for the purpose of extracting keywords from a document by not just considering a single document but all documents from the corpus. In terms of tf-idf a word … Continue reading → The post The tf-idf-Statistic For Keyword Extraction appeared first on joy...

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Easily generate correlated variables from any distribution

February 27, 2014
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Easily generate correlated variables from any distribution

In this post I will demonstrate in R how to draw correlated random variables from any distributionThe idea is simple.  1. Draw any number of variables from a joint normal distribution. 2. Apply the univariate normal CDF of variables to derive pro...

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More time series data online

February 27, 2014
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Earlier this week I had coffee with Ben Fulcher who told me about his online collection comprising about 30,000 time series, mostly medical series such as ECG measurements, meteorological series, birdsong, etc. There are some finance series, but not ma...

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Vertical Histogram

February 26, 2014
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Vertical Histogram

In the process of munging data for my current project I came across the need to compare (visually) the difference between two modes within the same dataset. I was using a simple scatterplot and setting the alpha in the hopes that the over-plotting woul...

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Type I error rates in test of normality by simulation

February 26, 2014
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Type I error rates in test of normality by simulation

This simulation tests the type I error rates of the Shapiro-Wilk test of normality in R and SAS. First, we run a simulation in R. Notice the simulation is vectorized: there are no "for" loops that clutter the code and slow the simulation. # type I erroralpha <- 0.05# number of simulationsn.simulations <- 10000#...

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Revolution Analytics named a Visionary in the Gartner Magic Quadrant for Advanced Analytics Platforms

February 26, 2014
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The entire team at Revolution Analytics is very proud to announce that Gartner has named Revolution Analytics a Visionary in the inaugural Gartner Magic Quadrant for Advanced Analytics Platforms, published February 19, 2014. The report evaluated 16 vendors through a series of stringent criteria related to the ability to execute and completeness of vision. Revolution Analytics is positioned the...

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Announcing Shiny Server Pro general availability

February 26, 2014
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Announcing Shiny Server Pro general availability

We are excited to announce the general availability of RStudio Shiny Server Pro. Shiny Server Pro is the simplest way for data scientists and R users in the enterprise to share their work with colleagues. With Shiny Server Pro you can: Secure access to Shiny applications with authentication systems such as LDAP and Active Directory

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Displaying spatial sensor data from Arduino with R on Google Maps

February 26, 2014
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Displaying spatial sensor data from Arduino with R on Google Maps

For Christmas I decided to treat myself with an Arduino starter kit. I started doing some basic experiments and I quickly found out numerous website that sell every sort of sensor: from temperature and humidity, to air quality. Long story short, I bou...

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