302 search results for "PCA"

7 new R jobs (2015-05-11)

May 11, 2015
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7 new R jobs (2015-05-11)

This is the bimonthly post (for 2015-05-11) for new R Jobs from R-users.com. Employers: visit this link to post a new R job to the R community (it’s free and quick). Job seekers: please follow the links below to learn more and apply for your job of interest (or visit previous R jobs posts). Full-Time Research & Analytics Manager Medallia, Inc. – Posted by pkriss Palo Alto California, United States 10...

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Odd Connections Inside The NASDAQ-100

May 8, 2015
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Odd Connections Inside The NASDAQ-100

Distinguishing the signal from the noise requires both scientific knowledge and self-knowledge (Nate Silver, author of The Signal and the Noise) Analyzing the evolution of NASDAQ-100 stock prices can discover some interesting couples of companies which share a strong common trend despite of belonging to very different sectors. The NASDAQ-100 is made up of 107 … Continue reading...

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Downloading and Visualizing Seismic Events from USGS

April 28, 2015
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Downloading and Visualizing Seismic Events from USGS

The unlucky events that took place in Nepal have flooded the web with visualization of the earthquakes from USGS. They normally visualize earthquakes with a colour scale that depends on the age of the event and a marker size that depends on magnitude. I remembered that some time ago I tested ways for downloading and visualizing data from USG...

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Accelerating R with multi-node parallelism – Rmpi, BatchJobs and OpenLava

Accelerating R with multi-node parallelism –  Rmpi, BatchJobs and OpenLava

Gord Sissons, Feng Li In a previous blog we showed how we could use the R BatchJobs package with OpenLava to accelerate a single-threaded k-means calculation by breaking the workload into chunks and running  them as serial jobs. R users frequently need to find solutions to parallelize workloads, and while solutions like multicore and socket

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Bias in Observational Studies – Sensitivity Analysis with R package episensr

April 18, 2015
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Bias in Observational Studies – Sensitivity Analysis with R package episensr

When it’s time to interpret the study results from your observational study, you have to estimate if the effect measure you obtained is the truth, if it’s due to bias (systematic error, the effect measure’s precision), or if it’s due to chance (random error, the effect measure’s validity) (Rothman and Greenland, 2008, pp115-134). Every study … Continue reading...

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Parallel R with BatchJobs

March 28, 2015
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Parallel R with BatchJobs

Parallelizing R with BatchJobs – An example using k-means Gord Sissons, Feng Li Many simulations in R are long running. Analysis of statistical algorithms can generate workloads that run for hours if not days tying up a single computer. Given the amount of time R programmers can spend waiting for results, getting acquainted parallelism makes

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Growing some Trees

March 18, 2015
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Growing some Trees

Consider here the dataset used in a previous post, about visualising a classification (with more than 2 features), > MYOCARDE=read.table( + "http://freakonometrics.free.fr/saporta.csv", + header=TRUE,sep=";") The default classification tree is > arbre = rpart(factor(PRONO)~.,data=MYOCARDE) > rpart.plot(arbre,type=4,extra=6) We can change the options here, such as the minimum number of observations, per node > arbre = rpart(factor(PRONO)~.,data=MYOCARDE, + control=rpart.control(minsplit=10)) > rpart.plot(arbre,type=4,extra=6) or...

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How to Make a Histogram with ggplot2

March 12, 2015
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How to Make a Histogram with ggplot2

In our previous post you learned how to make histograms with the hist() function. You can also make a histogram with ggplot2, “a plotting system for R, based on the grammar of graphics”. This post will focus on making a Histogram With ggplot2. Want to learn more? Discover the DataCamp tutorials. Step One. Check That The post

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Visualising a Classification in High Dimension

March 6, 2015
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Visualising a Classification in High Dimension

So far, when discussing classification, we’ve been playing on my toy-dataset (actually, I should no claim it’s mine, it is inspired by the one used in the introduction of Boosting, by Robert Schapire and Yoav Freund). But in ral life, there are more observations, and more explanatory variables.With more than two explanatory variables, it starts to be more complicated...

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Getting a statistics education: Review of the MSc in Statistics (Sheffield)

February 14, 2015
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Getting a statistics education: Review of the MSc in Statistics (Sheffield)

Some background:I started using statistics for my research sometime in 1999 or 2000. I was a student at Ohio State, Linguistics, and I had just gotten interested in psycholinguistics. I knew almost nothing ...

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