Publications by dylan
Un-Wrapping a Sphere with R
Premise I was recently asked to print out a fabric pattern that could be used to cover a sphere, about the size of a ping pong ball, for the purposes of re-creating a favorite cat toy (quite important). Thinking this over, I realized that this was basically a map projection problem– and could probably be solved by scaling an interrupted sinusoi...
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Estimated Net Worth of SoilWeb- Our Online Soil Survey
According to the excellent source code evaluation tool, SLOCCount, our online soil survey (SoilWeb) code is worth about $268,543 and would require about 2 years of development time to re-create from scratch with a single developer working full-time. This is a fairly close estimate, as I have been working (part-time) on this code-base for 3 years ...
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Interesting use of levelplot() for time series data
levelplot example: soil temperature (left) and moisture (right) Several recent articles appeared on the R-bloggers feed aggregator that demonstrated an interesting visualization of time series data using color. This style of visualization was readily adapted for the time series data I regularly collect (soil moisture and temperature), and quickly...
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Updates to SoilWeb
Soil Profiles in Color Added color support to the mini-profiles used in graphical map unit summaries, the Google Earth interface, and iPhone application. SSURGO doesn’t contain soil color data, so colors (in Munsell notation) were extracted from the OSD database, and converted into RGB triplets. Using horizon information from the OSD database a...
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Two New Soils-Related KMZ Demos
LCC KMZ Soil Texture KMZ Forgot to post these KMZ files: 1-km scale, aggregate LCC and soil texture data, derived from SSURGO. These are part of a series of KMZ / raster datasets that will be published soon. See attached files at the bottom of the page. Enjoy! read more Related To leave a comment for the author, please follow the link and comm...
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Visual Interpretation of Principal Coordinates (of) Neighbor Matrices (PCNM)
Principal Coordinates (of) Neighbor Matrices (PCNM) is an interesting algorithm, developed by P. Borcard and P. Legendre at the University of Montreal, for the multi-scale analysis of spatial structure. This algorithm is typically applied to a distance matrix, computed from the coordinates where some environmental data were collected. The resulti...
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Numerical Integration/Differentiation in R: FTIR Spectra
Stumbled upon an excellent example of how to perform numerical integration in R. Below is an example of piece-wise linear and spline fits to FTIR data, and the resulting computed area under the curve. With a high density of points, it seems like the linear approximation is most efficient and sufficiently accurate. With very large sequences, it ma...
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SoilWeb iPhone App: Beta-Testers?
iPhone App Screenshot rev 0.2 – icon iphone App Screenshot rev 0.2 – in Fresno More Updates: The application is now available on the Apple iTunes Store. Preliminary documentaion here. read more Related To leave a comment for the author, please follow the link and comment on their blog: dylan's blog. R-bloggers.com offers daily e-mail up...
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Yet Another plyr Example
another plyr example quantiles (0.05, 0.25, 0.5, 0.75, 0.95) of DSC by temperature bin There are plenty of good examples on how to use functions from the plyr package. Here is one more, demonstrating how to use ddply with a custom function. Note that there are two places where the example function may blow up if you pass in poorly formatted or st...
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Accessing Climate Change Data and a Custom Panel Function for Filled Polygons
GCS Model Grids Recently finished some collaborative work with Vishal, related to visualizing climate change data for the SEI. This project was funded in part by the California Energy Commission, with additional technical support from the Google Earth Team. One of the final products was an interactive, multi-scale Google Earth application, based...
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