# 2900 search results for "twitter"

## What are the distributions on the positive k-dimensional quadrant with parametrizable covariance matrix? (bis)

April 3, 2012
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$What are the distributions on the positive k-dimensional quadrant with parametrizable covariance matrix? (bis)$

Wondering about the question I posted on Friday (on StackExchange, no satisfactory answer so far!), I looked further at the special case of the gamma distribution I suggested at the end. Starting from the moment conditions, and the solution is (hopefully) given by the system The resolution of this system obviously imposes conditions on those

## Transaction Cost and Execution Price functionality in the Backtesting library in the Systematic Investor Toolbox

April 2, 2012
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I want to introduce the Transaction Cost and Execution Price functionality in the Backtesting library in the Systematic Investor Toolbox. The Transaction Cost is implemented by a commission parameter in the bt.run() function. You may specify the commissions in \$ per share for “share” type backtest and as a percentage of total trade for “weight”

## Web-Scraping in R

April 2, 2012
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Web-scraping, or web-crawling, sounds like a seedy activity worthy of an Interpol investigative department. The reality, however, is far less nefarious. Web-scraping is any procedure by which someone extracts data from the internet. Given that it’s possible to get the internet on computers these days; web-scrapping opens an array of interesting possibilities to social-science researchers

## An unabashedly narcissistic data analysis of my own tweets. The…

April 2, 2012
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pie( table( whence.i.tweet )) qplot( whence ) + coord_polar() pie( log( table( whence )))+RColorBrewer ggplot (see below) plot( density( tweets.len )) qplot(... stat="density") + geom_density qplot(...stat="bin") + geom_text(...) tweeple tweep...

April 1, 2012
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Hadley Wickham (@hadleywickham) this week mentioned on Twitter his preference for saveRDS() over the more familiar save(). Being a new function to me, I thought I’d take a look… save() and load() will be familiar to many R users. They … Continue reading →

April 1, 2012
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Hadley Wickham (@hadleywickham) this week mentioned on Twitter his preference for saveRDS() over the more familiar save(). Being a new function to me, I thought I’d take a look…

## Julia, I Love You

March 31, 2012
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Julia is a new language for scientific computing that is winning praise from a slew of very smart people, including Harlan Harris, Chris Fonnesbeck, Douglas Bates, Vince Buffalo and Shane Conway. As a language, it has lofty design goals, which, if attained, will make it noticeably superior to Matlab, R and Python for scientific programming.

## R-bloggers

March 29, 2012
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OK, like the nightclub Kenan and Kel founded in Rigby’s shop, we all know this blog is ‘duh bomb’ (or will be as I add more than my solitary post). However, there are other good R blogs. I thoroughly recommend signing up to the R-b...

## Social Network Analysis with R

March 27, 2012
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By Yanchang Zhao, RDataMining.com If you have tried social network analysis or graph mining with R, you might have already come across package igraph before. The package is designed for graphs and network analysis in R. It can handle large … Continue reading →

## Installing and Running JAGS on Mac OS 10.5.8

March 26, 2012
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JAGS is an alternative to BUGS (WinBUGS or OpenBUGS) for conducting a Bayesian Analysis. It stands for Just Another Gibbs Sampler, and like WinBUGS, it is essentially an MCMC machine that employs a Gibbs sampler so you don’t have to … Continue reading →