On Stackoverflow I found this useful example on how to apply custom statistics on a dataframe and return the results as list or dataframe:somedata<- data.frame( ...

David Varadi have recently wrote two posts about Gini Coefficient: I Dream of Gini, and Mean-Gini Optimization. I want to show how to use Gini risk measure to construct efficient frontier and compare it with alternative risk measures I discussed previously. I will use Gini mean difference risk measure – the mean of the difference

The companion web site for Serious Stats is now live:http://www.palgrave.com/psychology/baguley/The web site includes:- a free sample chapter (Chapter 15: Contrasts)- data sets- R scripts- 5 online supplements (for meta-analysis, multiple imputation, r...

Maxim's iButton Thermochron temperature dataloggers are little silver doo-dads the size of a large watch battery that can record up to 2048 time-stamped temperature values. The internal battery is usually good for a few years of use. Maxim supplies a J...

This post is a slightly revised (and "blogified") version of the message Brian Peterson has sent to various R mailing lists.Once again, R has been accepted as a mentoring organization for the Google Summer of Code (2012). We invite students interested in this program to learn more about it. A good starting point...

Compared to many other languages of equal popularity, there are realtively few development environments for R. In fact, the total number of production ready R IDEs could probably be counted on one hand. That deficiency is a small price to pay to use R and if you’re not already accustomed to using IDEs for other The post RStudio...

Ed Chen is a data scientist at Twitter, so he's accustomed to working with big data and complex models. In an interview with MIT Technology Review, he describes his data science toolbox: A common pattern for me is that I'll code a MapReduce job in Scala, do some simple command-line munging on the results, pass the data into Python...

Does minimum variance act differently from low volatility? Do either of them act like low beta? What about high volatility versus high beta? Inspiration Falkenblog had a post investigating differences in results when using different strategies for low volatility investing. Here we look not at a single portfolio of a given strategy over time, but … Continue reading...

The forecast package uses the base R graphics for all plots, but some people may prefer to use the nice graphics available using the ggplot2 package. In the following two posts, Frank Davenport shows how it can be done: Plotting forecast() objects in ...

n! means n x (n - 1) x ... x 3 x 2 x 1For example, 10! = 10 x 9 x ... x 3 x 2 x 1 = 3628800,and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.Find the sum of the di...

I found out that last.fm had made data files available for their Best of 2011 artist list, and I thought it’d be a great opportunity to learn some more about data management in R and Ggplot2. I began by downloading and importing the tab separated data file from last.fm (TSV). 1 2# read data lastfm <- read.delim("~/Downloads/bestof_2011_tsv/bestof_2011_releases.tsv") Then I did some data cleanup, because...

The following function "exp.mat" allows for the exponentiation of a matrix (i.e. calculation of a matrix to a given power). The function follows three steps:1) Singular Value Decomposition (SVD) of the matrix2) Exponentiation of the singular values3) Re-calculation of the matrix with the new singular valuesThe most common case where the method is applied...

Rainer pointed out, in response to my post, Row names in data frames: Beware of 1:nrow, that if I’d used rownames(x) <- as.character(1:3) rather than rownames(x) <- 1:3, I wouldn’t have had the problem I’d seen. If you type rownames(x) you see the same result as rownames(z), and is.character(rownames(x)) and is.character(rownames(z)) both return TRUE, but

Monday, March 26, 2012 14h-16h, Stewart Biology N4/17 Corey Chivers, Department of Biology McGill University This is a meetup of the Montreal R User Group. Be sure to join the group and RSVP. More information about the workshop here. Topics Why would we want to be Bayesian in the first place? In this workshop we