Monthly Archives: January 2012

Reproducible Research with R: Cost of energy and mutual shadows in a two-axis tracking PV system

January 1, 2012
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Some days ago the journal Renewable Energy published my last paper “Cost of energy and mutual shadows in a …Continuar leyendo »

Decoding a Substitution Cipher using Simulated Annealing

January 1, 2012
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$Decoding a Substitution Cipher using Simulated Annealing$

My last post discussed a method to decode a substitution cipher using a Metropolis-Hastings algorithm. It was brought to my attention that this code could be improved by using Simulated Annealing methods to jump around the sample space and avoid some of the local maxima. Here is a basic description of the difference: In a

R-Function to Source all Functions from a GitHub Repository

January 1, 2012
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Here's a function that sources all scripts from an arbitrary github-repository. At the moment the function downloads the whole repo and sources functions kept in a folder named "Functions" - this may be adapted for everyones own purpose.# Script name: ...

NIPALS: Principal Components Analysis with "R" (Part: 002)

January 1, 2012
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We started some posts based on the tutorials of:"Multivariate Statistical Analysis using the R package chemometrics"The first post was:Principal Components Analysis with "R" (Part: 001)Now we continue with a second part.The graphics help us to dec...

Top 20 R posts of 2011 (and some R-bloggers statistics)

January 1, 2012
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R-bloggers.com is now two years young. The site is an (unofficial) online R journal written by bloggers who agreed to contribute their R articles to the site. In this post I wish to celebrate R-bloggers’ second birthmounth by sharing with you: Links to the top 20 posts of 2011 Statistics on “how well” R-bloggers did Read more...

Monetary Policy & Credit Easing pt. 7: R Econometrics Tests

January 1, 2012
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In post 6 we introduced some econometrics code that will help those working with time-series to gain asymptoticly efficient results.  In this post we look at the different commands and libraries necessary for testing our assumptions and such. Testing our Assumptions and Meeting the Gauss-Markov TheoremIn this section we will seek to test and verify the assumptions of the simple linear...

Free Online Stanford Machine Learning Course: Andrew Ng. Post Mortem.

January 1, 2012
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Happy New Year to all the viewers of this blog and just a short reminder that the course will be available again this January.http://www.ml-class.org/course/auth/welcomeHaving audited the course, I would highly recommend it to anyone who is interested ...

RTextTools v1.3.5: Saving models, text labels, and a game plan for 2012

RTextTools v1.3.5 addresses some key concerns that have been raised in recent months. Many of the algorithms used in RTextTools require that any new data presented to a trained classifier contain the same features as the original document-term matrix. Since this rarely (if ever) happens in the real world, I have added an originalMatrix parameter to the create_matrix() function...

RTextTools v1.3.5: Saving models, text labels, and a game plan for 2012

RTextTools v1.3.5 addresses some key concerns that have been raised in recent months. Many of the algorithms used in RTextTools require that any new data presented to a trained classifier contain the same features as the original document-term matrix. Since this rarely (if ever) happens in the real world, I have added an originalMatrix parameter to the create_matrix() function...