Publications by dylan
InfoChimps
This looks interesting: http://infochimps.org/search?query=soil 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 updates about R news and tutorials about learning R and many other topics. Click here if you're looking to post or find an R/data-science ...
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Estimating Missing Data with aregImpute() {R}
Missing Data Soil scientists routinely sample, characterize, and summarize patterns in soil properties in space, with depth, and through time. Invariably, some samples will be lost or sufficient funds required for complete characterization can run out. In these cases the scientist is left with a data table that contains holes (so to speak) in the...
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Converting Alpha-Shapes into SP Objects
Just read about a new R package called alphahull (paper) that sounds like it might be a good candidate for addressing this request regarding concave hulls. Below are some notes on computing alpha-shapes and alpha-hulls from spatial data and converting the results returned by ashape() and ahull() into SP-class objects. Note that the functions are ...
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Annotating Lattice Box and Whisker Plots
bwplot annotation example Sometimes you want to add a little text to box and whisker plots produced by the lattice function bwplot(). Here is one approach. Could be optimized a bit more to reduce manual specification of some elements. Suggestions welcomed. read more Related To leave a comment for the author, please follow the link and comment o...
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SQLite as an alternative to shapefiles, and some GPS fun in R
Finally made it out to Folsom Lake for a fine day of sailing and GPS track collecting. Once I was back in the lab, I downloaded the track data with gpsbabel, and was ready to import the data into GRASS. # import GPX from GPS: gpsbabel -t -i garmin -f /dev/ttyS0 -o gpx -F trip1.gpx I was particularly interested in how fast we were able to get the...
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Getting Parent Material Data out of SSURGO
Parent material data is stored within the copm and copmgrp tables. The copm table can be linked to the copmgrp table via the ‘copmgrpkey’ field, and the copmgrp table can be linked to the component table via the ‘cokey’ field. The following queries illustrate these table relationships, and show one possible strategy for extracting the par...
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An XML Representation of the Keys to Soil Taxonomy?
Western Fresno Soil Hierarchy: partial view of the hierarchy within the US Soil Taxonomic system Maybe this is just craziness, but wouldn’t be neat to have an XML formatted version of the Keys to Soil Taxonomy? The format might look something like the following code snippet, although there may be more efficient uses of XML… The only problem I...
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PostGIS in Action Book Review
I was recently asked to review a soon to be published book on PostGIS, a spatial extension to the very popular Postgresql relational database. I was very excited about receiving an early copy of this book, as the authors have provided countless tips, fixes, and clever query examples on the PostGIS mailing list over the years. After spending a cou...
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Updated SoilWeb for the iPhone + Alpha Android Version
Major updates to the SoilWeb iPhone Application. 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 updates about R news and tutorials about learning R and many other topics. Click here if you're looking to post or find an R/data-science job. ...
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R’s Normal Distribution Functions: rnorm and pals
The rnorm() function in R is a convenient way to simulate values from the normal distribution, characterized by a given mean and standard deviation. I hadn’t previously used the associated commands dnorm() (normal density function), pnorm() (cumulative distribution function), and qnorm() (quantile function) before– so I made a simple demo. Th...
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