2636 search results for "gis"

Observing Dark Worlds – Visualizing dark matter’s distorting effect on galaxies

October 13, 2012
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Observing Dark Worlds – Visualizing dark matter’s distorting effect on galaxies

Some people like to do crossword puzzles. I like to do machine learning puzzles. Lucky for me, a new contest was just posted yesterday on Kaggle. So naturally, my lazy Saturday was spent getting elbow deep into the data. The training set consists of a series of ‘skies’, each containing a bunch of galaxies. Normally,

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How to choose the right *apply function

October 13, 2012
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How to choose the right *apply function: This is an amazing stackoverflow answer to help you decide which of the many *apply functions (apply, lapply, sapply, vapply, mapply, rapply, tapply) is appropriate for the task at hand. I’m planning on doing...

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Using cairographics with ggsave()

October 12, 2012
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Using cairographics with ggsave()

Whenever possible, I try to save R graphic output in a vector format, typically pdf(). I also like to use the handy ggsave() function to do so, as it streamlines the process, and makes it easy to be consistent across formats. However, at times it is n...

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Revolution Newsletter: September/October 2012

October 11, 2012
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The most recent edition of the Revolution Newsletter is out. The news section is below, and you can read the full September/October edition (with highlights from this blog and community events) online. You can subscribe to the Revolution Newsletter to get it monthly via email. New R Courses Announced: Two new courses presented by Bob Muenchen (author of R...

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Random Name Generator in R

October 11, 2012
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Just for the heck of it, let's recreate my Reality TV Show Name Generator in R. This isn't really the sort of thing you'd normally do in R, but we can try out a bunch of different functions this way: random integers/sampling, concatenation, sorting, an...

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Pilot Study: Small Town Land Surface Temperature

October 11, 2012
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Pilot Study: Small Town Land Surface Temperature

Introduction Zhang and Imhoff (2010)  pdf here utilized NLCD impervious surface area (ISA), Olson biomes, and MODIS Land Surface temperature (LST) to estimate the magnitude of UHI in large cities across the US.  Peng  employed a   similar approach in studying 419 large cities ( population greater than 1m ) around world. Peng’s work suggests a limit

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From holey polygons to convex hulls

October 11, 2012
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From holey polygons to convex hulls

I only rarely have the occasion to need the convex hull of a set of points, but I love chull(), so I’d like to share an example of how to use it. This Gist also offers a pretty straightforward application of the Split-Apply-Combine strategy (see...

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Simple marimekko/mosaic plots

October 10, 2012
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Simple marimekko/mosaic plots

I don’t really care for the name “marimekko” or “mosaic,” but I do like this type of plot as a means of illustrating proportions in nested categorical data, or as an alternative to the parallel time series plots discussed...

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Making Color Ramps in Matlab

October 9, 2012
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When visualizing an array of data in a heatmap, a good color map makes a world of difference.Thanks to my work in 'omics (i.e. transcriptomics - microarrays and RNASeq) I've looked at a lot of heatmaps over the past couple of years, and generated quite...

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Age-Period-Cohort models and the decline of violence

October 9, 2012
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Age-Period-Cohort models and the decline of violence

Ever since the end of the Mexican Revolution and the Cristero War violence in Mexico inched down in fits and starts from a high of about 60 homicides per 100,000 people to its lowest level sometime during the middle of the last decade (there's some uncertainty about the number of homicides in...

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