Monthly Archives: December 2009

NCEP Global Forecast System

December 16, 2009
By
NCEP Global Forecast System

Just about everyone is familiar with weather maps. There are many situations where it is useful to combine the underlying numerical weather data with other types of information. Accessing  the weather data is a necessary first step. The output from the U.S. National Centers for Environmental Prediction (NCEP) Global  Forecast System (GFS) is freely available.

Read more »

email yourself when a script or a job is done

December 15, 2009
By

i usually run long simulations in R on a remote server. i’ve read an article on linux journal about emailing yourself after something happens…i forgot. since my jobs are long, and i usually have to run multiple jobs sequentially, it’d be nice to look at my results immediately when they’re gone. good thing *nix based

Read more »

R Site Search with the ‘sos’ Package

December 15, 2009
By

REvolution Computing is a sponsor of the Bay Area R User Group, which gathered on Tuesday for its monthly meeting. This month's meeting was in a cozy setting at San Jose State University, and was hosted by David Czerwinski who teaches data mining there. The topic at hand was search, and finding R packages to compliment the functionality requirements...

Read more »

Browse R Graphics with the R Graph Gallery and the R Graphical Manual

December 15, 2009
By

One of R's biggest strengths is its unparalleled graphing capabilities.  Just see any of our previous posts on ggplot2, visualization, or other posts tagged with R. R has several fundamentally different systems for plotting, including base graphics, lattice, and ggplot2.  Furthermore, many add-on packages come with their own functions for producing problem-domain specific graphics. For example,

Read more »

R Tutorial Series: Graphic Analysis of Regression Assumptions

December 15, 2009
By
R Tutorial Series: Graphic Analysis of Regression Assumptions

An important aspect of regression involves assessing the tenability of the assumptions upon which its analyses are based. This tutorial will explore how R can help one scrutinize the regression assumptions of a model via its residuals plot, normality h...

Read more »

Object-Oriented Programming in R: The Setter Methods

December 14, 2009
By

With a little guidance from the indefatigable Hadley Wickham, I figured out today how to implement the setter methods that were missing from my example user class. To review, let’s rebuild the getter methods for my user object: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Read more »

NYT on breast cancer screening and probability

December 14, 2009
By

The New York Times last weekend looked at the controversy around the recent changes to the mammogram guidelines from a mathematical perspective. Compared to the analysis based on Bayes' Theorem from the Harvard Social Science Statistics blog (which apparently caused some controversy itself: that post was deleted and later replaced after some errors apparently crept into the calculations), this...

Read more »

The Grammar of Graphics: ggplot2 package

December 14, 2009
By

The grammar of graphics approach to constructing graphs has been implemented in the ggplot2 package in R. The author of the package, Hadley Wickham, has provided a website with many details of using the system to create nice looking graphics. The package removes many of the awkward parts of setting up graphical display that characterise other

Read more »

R 2.10.1 released

December 14, 2009
By

The latest update to R, R 2.10.1, is now available for download in source form from your local CRAN mirror. Binary versions (for Mac, Windows, and Linux) will become available over the next few days. As a maintenance release, this update focuses on minor changes and bug fixes. The complete list of changes is available in the NEWS file,...

Read more »

Example 7.18: Displaying missing value categories in a table

December 14, 2009
By
Example 7.18: Displaying missing value categories in a table

When displaying contingency tables (section 2.3.1), there are times when it is useful to either show or hide the missing data category. Both SAS and the typical R command default to displaying the table only for observations where both factors are observed.In this example, we generate some multinomial data (section 1.10.4) and then produce tables with and without...

Read more »