Blog Archives

Interesting use of levelplot() for time series data

January 16, 2010
By
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...

Read more »

Estimated Net Worth of SoilWeb- Our Online Soil Survey

December 28, 2009
By

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 now...

Read more »

Un-Wrapping a Sphere with R

December 8, 2009
By
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...

Read more »

New R-Forge Site for Quantitative Pedology

November 8, 2009
By
New R-Forge Site for Quantitative Pedology

Just back from the annual meetings, and it looks like there is a significant interest in collaborative R coding of soils-related algorithms and visualization. A new R-forge site has been created to host Algorithms for Quantitative Pedology. Public release of the 'soil' package should be ready in a couple weeks. Soil Profile Dendrogram

Read more »

Aggregating SSURGO Data in R

September 10, 2009
By
Aggregating SSURGO Data in R

  Premise SSURGO is a digital, high-resolution (1:24,000), soil survey database produced by the USDA-NRCS. It is one of the largest and most complete spatial databases in the world; and is available for nearly the entire USA at no cost. These data are distributed as a combination of geographic and text data, representing soil map units and their...

Read more »

Potential Loss of Arable Land in the Central San Joaquin Valley, CA

August 17, 2009
By
Potential Loss of Arable Land in the Central San Joaquin Valley, CA

Rapid urban and sub-urban expansion in the San Joaquin Valley have resulted in the loss of millions of acres of prime farmland in the last 100 years. Approximately 11% of class 1 (irrigated) land and 7% of class 2 land have already been paved over in the Fresno-Madera region (first image below). Recent projections in the expansion of urban...

Read more »

Computing Statistics from Poorly Formatted Data (plyr and reshape packages for R)

July 9, 2009
By

  Premise I was recently asked to verify the coefficients of a linear model fit to sets of data, where each row of the input file was a "site" and each column contained the dependent variable through time (i.e. column 1 = time step 1, column 2 = time step 2, etc.). This format is cumbersome in that it...

Read more »

Using R to Create Misc. Patterns [smocking]

July 4, 2009
By
Using R to Create Misc. Patterns [smocking]

Pattern Chunk   Premise My wife asked me to come up with some graph paper for creating smocking patterns. After a couple of minutes playing around with R-base graphics functions, it occurred to me that several functions in the sp package...

Read more »

Summarizing Grouped Data in R

July 3, 2009
By

A colleague of mine recently asked about computing basic summary statistics from grouped data in R. These are a couple examples that I suggested. Additional documentation for the plyr package can be found here. read more

Read more »

Accessing Soil Survey Data via Web-Services

May 28, 2009
By
Accessing Soil Survey Data via Web-Services

Soil Survey Data   Online Querying of NRCS Soil Survey Data Sometimes you are only interested in soils data for a single map unit, component, or horizon. In these cases downloading the entire survey from Soil Data Mart is not worth the effort. An...

Read more »