Monthly Archives: March 2010

R: Eliminating observed values with zero variance

March 8, 2010
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R: Eliminating observed values with zero variance

I needed a fast way of eliminating observed values with zero variance from large data sets using the R statistical computing and analysis platform. In other words, I want to find the columns in a data frame that has zero variance. And as fast as possible, because my data sets are large, many, and changing fast....

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R: Eliminating observed values with zero variance

March 8, 2010
By
R: Eliminating observed values with zero variance

I needed a fast way of eliminating observed values with zero variance from large data sets using the R statistical computing and analysis platform. In other words, I want to find the columns in a data frame that has zero variance. And as fast as possible, because my data sets are large, many, and changing fast....

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InfoChimps

March 7, 2010
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InfoChimps

This looks interesting: http://infochimps.org/search?query=soil

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ggplot and concepts — what’s right, and what’s wrong

March 7, 2010
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ggplot and concepts — what’s right, and what’s wrong

A few months back I gave a presentation to the NYC R Meetup. (R is a statistical programming language. If this means nothing to you, feel free to stop reading now.) The presentation was on ggplot2, a popular package for generating graphs of data and statistics. In the talk (which you can see here, including

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A nice link: “Some hints for the R beginner”

March 7, 2010
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Patrick Burns just posted to the mailing list the following massage: There is now a document called “Some hints for the R beginner” whose purpose is to get people up and running with R as quickly as possible. Direct access to it is: http://www.burns-stat.com/pages/Tutor/hints_R_begin.html JRR Tolkien wrote a story (sans hobbits) called ‘Leaf by Niggle’ that has always resonated with me. I...

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One R Tip A Day meets Tecnica Arcana

March 7, 2010
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One R Tip A Day meets Tecnica Arcana

For italian speaking people only (sorry!). Carlo il curatore dell'ottimo podcast tecnologico Tecnica Arcana mi ha intervistato sulla mia professione e su R. Qui potete scaricare l'intervista in formato mp3.

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Ecological Modelling with “R”

March 7, 2010
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Here i present some Books and Articles about Ecological Modelling and “R”. Since “R” is integrated in Bio7 all the presented methods in the Books and Articles can also be useful together with Bio7. Books: Ellner, Stephen P. & Guckenheimer, John (2006). Dynamic Models in Biology. Princeton University Press Bolker B (2008) Ecological Models and

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Intermarket Whac-A-Mole

March 6, 2010
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Intermarket Whac-A-Mole

Every trader that looks at more than one market throughout the day will recognize that there is a certain symmetrical relationship between certain markets at certain times. The confounding thing about these intermarket relationships is that they are fl...

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schoolmath

March 6, 2010
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schoolmath

In connection with the Le Monde puzzle of last week, I was looking for an R function that would give me the prime factor decomposition of any integer. Such a function exists within the package schoolmath, developped by Joerg Schlarmann and Josef Wienand. It is called prime.factor and it returns the prime factors of any

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Visualizing Drought

March 6, 2010
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Visualizing Drought

The impacts of drought depend on time-scale. On short time-scales, drought means dry soil. On long time-scales, it means dry rivers and empty reservoirs. A region may simultaneously experience dry conditions on one time-scale and wet conditions on another e.g. wet soil but low streamflow or visa versa. Standardized Precipitation Index (SPI) is a widely

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