Blog Archives

Correlation Primer with Aster and R

December 20, 2016
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Calculating correlations is often starting point before more advanced analytical steps take place. Big data (long data) always presents computational challenges of both scale and distributed nature. In turn they may get aggravated by the presence of large number of features (wide data). But challenges do not stop here as complex relationships induce analysis of correlations across subsets and groups....

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Running similar but independent jobs in parallel on Aster with R

May 31, 2016
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Running similar but independent jobs in parallel on Aster with R

No surprise that Teradata Aster runs each SQL, SQL-MR, and SQL-GR command in parallel on many clusters with distributed data. But when faced with the task of running many similar but independent jobs one has to do extra work to parallelize them in As...

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Map of the Windows Fonts Registered with R

April 24, 2016
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Map of the Windows Fonts Registered with R

If you already found package extrafont then you probably found how to load and use Windows fonts in R visualizations. But just in case, everything to get started with extrafont is found here and summarized for using fonts in Windows for on-screen or bitmap output below:One thing to add is a summary of all Windows fonts registered in R. This will come handy...

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Creating and Tweaking Bubble Chart with ggplot2

April 16, 2016
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Creating and Tweaking Bubble Chart with ggplot2

This article will take us step-by-step over incremental changes to produce a bubble chart using ggplot2 that looks like this:We'll encounter the plot above once again at the very end after explaining each step with code changes and observing intermediate plots. Without getting into details what it means (curios reader can find out here)...

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R Graph Objects: igraph vs. network

January 30, 2016
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R Graph Objects: igraph vs. network

While working on new graph functions for my package toaster I had to pick from the R packages that represent graphs. The choice was between network and graph objects from the network and igraph correspondingly - the two most prominent packages for creating and manipulating graphs and networks in R.Interchangeability of network and graph objectsOne can always use them interchangeably with...

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VW Big Data Play

September 22, 2015
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Volkswagen made headlines lately for cheating U.S. EPA regulators. But let's pay some respect to their engineers.Apparently, there is no button or switch that tells car it's being tested - indeed - that would be obvious flaw in the emission test protoc...

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How to expand color palette with ggplot and RColorBrewer

September 12, 2013
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How to expand color palette with ggplot and RColorBrewer

Histograms are almost always a part of data analysis presentation. If it is made with R ggplot package then it may look like this:data(mtcars) ggplot(mtcars) + geom_histogram(aes(factor(cyl), fill=factor(cyl)))The elegance of ggplot functions is in simple yet compact expression of visualization formula while hiding many options...

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Quick R tip: ggplot in functions needs some extra care

July 31, 2013
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When building visualizations with ggplot2 in R I decided to create specialized functions that encapsulate plotting logic for some of my creations. In this case instead of commonly used aes function I had to use its alternative -  aes_string - for aesthetic mapping from a string.And now goes this handy tip:while original aesthetic mapping function aes accepts x and y parameters by...

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Gentle Intro to Octave or Matlab

June 4, 2012
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I began using Octave for homework assignments from the online Machine Learning class. Having worked with languages like Python, Groovy and JavaScript I never expected a system designed for numerical computations to include such a complete and unique programming language. But it does and I can't resist sharing some examples.There are two important things one should know...

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AutoComplete Using Google App Engine and YUI in two parts (part 2)

October 23, 2011
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AutoComplete Using Google App Engine and YUI in two parts (part 2)

Part 2: Autocomplete with YUI3 and GAE RPC HandlersThis is second and final part of 2-part series on implementing AutoComplete with GAE. Recall that in part 1 we built a foundation for keyword autocomplete lookup service for our document search application. Both the service itself and its HTML/JavaScript client will materialize below.Let's for a moment...

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