2149 search results for "twitter"

R + EC2 + RStudio Server

March 30, 2011
By
R + EC2 + RStudio Server

I’ve been battling memory limits in R for over two years. Although R has numerous resources for high-performance computing, I still couldn’t get around hardware limitations. Things really got out of control last summer when I started analyzing data on how climate change influences population synchrony across large spatiotemporal gradients. My datasets were simply too

Read more »

Le Monde puzzle [#8]

March 29, 2011
By
Le Monde puzzle [#8]

Another mathematical puzzle from Le Monde that relates to a broken calculator (skipping the useless tale): Given a pair of arbitrary positive integers (x,y) a calculator can either substract the same integer from both x and y or multiply either x or y by 2. Is it always possible to obtain equal

Read more »

merge with solaR

merge with solaR

The version 0.22 of solaR includes a new method, mergesolaR. It is designed to merge daily time series of several solaR objects. For example, we can obtain the daily irradiation of the whole set of meteorological stations of Madrid (Spain) and use this information to calculate the productivity of a grid connected PV system. It

Read more »

Time series

March 28, 2011
By
Time series

(This post got published on The Statistics Forum yesterday.) The short book review section of the International Statistical Review sent me Raquel Prado’s and Mike West’s book, Time Series (Modeling, Computation, and Inference) to review. The current post is not about this specific book, but rather on why I am unsatisfied with the textbooks in

Read more »

R [re-]exam

March 27, 2011
By
R [re-]exam

In what seems like an endless cuRse, I found this week I had to re-grade a dozen R exams a TA’s did not grade properly! The grades I (X) got are plotted below against those of my TA (Y). There is little connection between both gradings… As if this was not enough trouble, I also

Read more »

R-ecap [-16]

March 26, 2011
By
R-ecap [-16]

This morning, I noticed that none of my R related posts had appeared on R-bloggers for the past fortnight… After investigating, this was caused by…cut-and-paste! Indeed, when advertising about the special issue of TOMACS Arnaud Doucet and I edit about Monte Carlo methods in Statistics, I copied the main parts from the pdf announcement, straight

Read more »

“An R package” or “A R package”

March 26, 2011
By
“An R package” or “A R package”

I’m currently writing some lecture notes on R and I used the phrase “a R package” without thinking. Since the word following the article “a” was a consonant, I automatically went for “a” instead of “an”. The problem is that “R” sounds likes a vowel, so “a R package” grates on the listener. The correct

Read more »

solaR 0.22 is at CRAN

solaR 0.22 is at CRAN

The version 0.22 of solaR is now available at CRAN. Besides, solaR is now registered at R-Forge. A new mergesolaR method has been defined for merging solaR objects. The calculation of the sunset time has been improved. The voltage dependency of the efficiency curve of the inverter is now included in fProd and calcGCPV. The

Read more »

Le Monde puzzle [#7]

March 26, 2011
By
Le Monde puzzle [#7]

The mathematical puzzle from the weekend edition of Le Monde from a few weeks ago was not too hard to solve by induction but my R code failed miserably! The puzzle was as follows: A calculator is broken in such a way that it starts by exhibiting 0, then pressing 4, 6 or 0 keeps

Read more »

MCMC with errors

March 25, 2011
By
MCMC with errors

I received this email last week from Ian Langmore, a postdoc in Columbia: I’m looking for literature on a subject and can’t find it:  I have a Metropolis sampler where the acceptance probability is evaluated with some error.  This error is not simply error in evaluation of the target density.  It occurs due to the

Read more »