Monthly Archives: May 2011

Participate in the 2011 Rexer Data Mining Survey

May 23, 2011
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Last year's Rexer Data Mining Survey reported that R is used by more data miners than any other tool. If you're using R for data mining or data analysis generally, be counted at the 2011 Data Miner Survey (use access code: RL3X2), which closes in early June. Here's some background on the survey: The survey is conducted annually by...

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News about speeding R up

May 23, 2011
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News about speeding R up

The most visited post ever on the ‘Og was In{s}a(ne), my report on Radford Neal’s experiments with speeding up R by using different brackets (the second most populat was Ross Ihaka’s comments, “simply start over and build something better”). I just spotted two new entries by Radford on his blog that are bound to rekindle the

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Quantifying gravitational lensing by dark matter

May 23, 2011
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Quantifying gravitational lensing by dark matter

The latest prediction competition at Kaggle is literally "out of this world": the goal is to quantify the shape of 2-D images of galaxies from a simulated telescope, to test models for how invisible dark matter in the Universe distorts the images through gravitational lensing (as shown in the image below; see the FAQ for more details). If you're...

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Utility Spread and Financial Turbulence

May 23, 2011
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Utility Spread and Financial Turbulence

THIS IS NOT INVESTMENT ADVICE.  YOU ARE RESPONSIBLE FOR YOUR OWN GAINS AND LOSSES. In Long XLU Short SPY Part 2 (More History), I explored the defensive nature of the spread and its potential as a bond substitute in troublesome periods for stocks...

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May 2011 Guerrilla Classes: Light Bulb Moments

May 23, 2011
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It's impossible to know what will constitute a light bulb moment for someone else. In the recent Guerrilla classes (GBoot and GCaP), we seemed to be having many more than our usual quota of such moments. So much so, that I decided to keep a list. The first was mine. Asa H. was having trouble...

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New York, September 8/9, 2011 – Portfolio Selection and Optimization in Practice

May 23, 2011
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(This article was first published on Rmetrics blogs, and kindly contributed to R-bloggers) To leave a comment for the author, please follow the link and comment on their blog: Rmetrics blogs. R-bloggers.com offers daily e-mail updates about R news and tutorials on topics such as: Data science, Big Data, R jobs, visualization (ggplot2, Boxplots, maps, animation), programming (RStudio, Sweave,...

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Summarize Data by Several Variables

May 23, 2011
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Summarize Data by Several Variables

Here's an example how to conveniently summarize data with the cast function (package reshape). By the way you see how this could be done "in-conveniently" by hand. You also see how a for-loop works and how a matrix is constructed and fill...

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Preparing RTextTools Beta Release for Catania 2011

Right now our development team is busy preparing a conference release of RTextTools for The 4th Annual Conference of the Comparative Policy Agendas Project at the University of Catania in Sicily. One of the key issues we've had thus far is memory consumption with very large datasets.In the past week we've pushed out a slew of

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Specific differences between Ledoit-Wolf and factor models

May 22, 2011
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Specific differences between Ledoit-Wolf and factor models

What can we learn about the difference in structure between a Ledoit-Wolf variance matrix and a corresponding factor model variance? Previously We’ve generated a set of random portfolios with constraints on the risk fractions of a Ledoit-Wolf variance matrix, and a corresponding set of random portfolios with risk fraction constraints from a statistical factor model. … Continue reading...

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Legends in ggplot2

May 22, 2011
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Legends in ggplot2

A simple plot takes a few lines of coding:g1 <- ggplot(d, aes(birth.year))g2 <- g1 + geom_line(aes(y=alive0, linetype="Famale")) +  geom_line(aes(y=alive1, linetype="Male")) + scale_linetype_discrete(name = "")g3 <- g2 + geom_point(aes(y=...

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