# Monthly Archives: February 2009

## Illinois long-term selection experiment for oil and protein in corn

February 22, 2009
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Researchers at the University of Illinois are conducting one of the longest experiments in biology - Illinois long-term selection experiment for oil and protein in corn. The experiment started in 1896 and is still active! In esence they are selecting l...

## Project Euler Problem #13

February 21, 2009
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Problem 13 on Project Euler asks us to sum 100 50-digit numbers and give the first 10 digits of the result. This is pretty easy. Note we are using R’s integer division operator %/% to discard the remainder of the large summed integer and just giv...

## Project Euler Problem #14

February 21, 2009
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Problem 14 on the Project Euler site asks us to find the longest chain under 1 million created using the Collatz mapping. This is fairly straightforward, although performance again is not great: ## Problem 14 # Collatz conjecture problem14 <-&...

## Project Euler Problem #12

February 21, 2009
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Problem 12 on the Project Euler site asks: What is the value of the first triangle number to have over five hundred divisors? A triangular number T(n) is defined as . The R code below consists of a solution, which involves the fact that the number of proper divisors of an integer n can be

February 21, 2009
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## Registration for R/Finance 2009 is Open!

February 20, 2009
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The conference website has details on:the agenda and speakers,travel accommodations,registration, andsponsors, who made the conference possible.Hope to see you there!

## People who love scatter plots & connecting dots

February 20, 2009
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We hosted the first Dataviz Salon SF on Tuesday night, with lightning talks by boredom cop Shane Booth, dataviz wiz Lee Byron , computational journalist Brad Stenger, data wrangler Pete Skomoroch , and any/all data enthusiast Brendan O’Connor . I was going to blog all about it — but Tom Carden of Stamen Design already

## R: Good practice – adding footnotes to graphics

February 17, 2009
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In some statistical programs there is the option available to attach a footnote to the graphical output that is created. This footnote may contain the name of the script or the file that produced the graphic, the author’s name and the date of creation. In SAS for example there is a footnote command to achieve

## Pearson vs. Spearman Correlation Coefficients

February 17, 2009
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One of the misuses of statistical terminology that annoys me most is the use of the word “correlation” to describe any variable that increases as another variable increases. This monotonic trend seems worth looking for, but it plainly is not what m...

## TTR_0.2 on CRAN

February 15, 2009
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I am happy to announce a long-overdue update to the TTR package (version 0.2) is now on CRAN.This update represents a major milestone, as TTR useRs are no longer restricted to using matrix objects. TTR 0.2 uses xts internally, so all major time series...