2643 search results for "GIS"

Musings on Correlation (or yet another reason I fear for those non-methodologically inclined students in my cohort)

August 12, 2011
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Musings on Correlation (or yet another reason I fear for those non-methodologically inclined students in my cohort)

I’ve been thinking a lot about what it means for two variables to be correlated.  Scientists throw around the term like it’s uniformly understood, but I fear that an understanding of the concept is elusive to substantive researchers who aren’t interested in empirical methods, except as a means by which we can demonstrate that our

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High-Performance in Cloud Computing

August 11, 2011
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High-Performance in Cloud Computing

Very often scientists are worried about performance and security in cloud computing. Especially, when talking about High-Performance Computing (HPC) in the cloud it is a very important aspect to proof efficient calculation speed in the cloud. Cloud computing describes a new delivery model for IT services based on Internet protocols, and it typically involves provisioning

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ggplot2: Determining the order in which lines are drawn

August 11, 2011
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ggplot2: Determining the order in which lines are drawn

In a time series, I want to plot the values of an interesting cluster versus the background. However, if I'm not careful, ggplot will draw the items in an order determined by their name, so background items will obscure the interesting cluster: Corr...

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Climate datasets in R

August 10, 2011
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As an ecologist working on climate change questions, I’ve always found it rather tedious to acquire and process climate data, especially when dealing with large spatiotemporal scales. Although many agencies provide free access to climate data, there is often some overhead (typically one to two days) before the data are made available for download via

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In case you missed it: July Roundup

August 10, 2011
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In case you missed them, here are some articles from July of particular interest to R users. A simulation in R finds the value (or disadvantage) or drawing an X, J, Q or Z in Scrabble. How to display high-quality graphics on the web using SVG output from R. A review of Paul Murrell's talk about raster image support...

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Using the google prediction API from R

August 10, 2011
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Using the google prediction API from R

Google has a "black box" prediction API that they provide for use with creating recommender systems or filtering spam. Furthermore, they provide an R package for interfacing that API, but try as I might I cannot get it to work under windows. Here are ...

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Plotting molecular properties for (sub)sets

August 10, 2011
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Plotting molecular properties for (sub)sets

For a toxicology paper we are writing up, I need to create a few plots showing how the toxic and non-toxic molecules differ (or not) with respect to a few molecular properties, such as logP or the molecular weight. The rcdk package provides all, of cou...

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Scraping web data in R

August 10, 2011
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Scraping web data in R

In my last post, I went through a lot of effort to scrape the PMI index off the ISM website.  It turns out that was unnecessary effort, as commentator "senne" pointed out that this index is available from FRED, with the symbol NAPM. &nbs...

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Multiple cores in R, revisited

August 10, 2011
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The bigmemory package in combination with doMC provides at least a partial solution for sharing a large data set across multiple cores in R. With this solution you can work on the same matrix using several threads. It is also a very scalable solution. ...

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Forecasting recessions

August 9, 2011
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Forecasting recessions

John Hussman has a Recession Warning Composite that I am attempting to replicate/improve. The underlying data seems to be easy enough to get from FRED using the quantmod package in R. I don't quite understand the index Hussman is using for commercial...

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