Monthly Archives: July 2012

New package RcppCNPy with release 0.1.0 (and 0.0.1 earlier last week)

A few days ago I had blogged about getting NumPy data in R by using a simple converter script. That works fine, but it is a little annoying to have to write an entire file only to read from it again. So I kept looking around for a better solution---and soon found the cnpy library by Carl Rogers which provides simple C++...

Representation of numerical NA’s in R and the 1954 enigma

July 8, 2012
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I've always wondered how exactly the missing value (NA) in R is represented under the hood. Last weekend I was working on a little project that gave me enough excuse to spend some time on finding this out. So, I … Continue reading →

Fitting a dynamic model, and determining the number of parameters that can be fitted.

July 8, 2012
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Let's suppose that we have the same dynamic model we presented before - that is, the Lorentz system of differential equations. Remember? In order to perform a fitting we need to define an objective function of sort: this will then be minimised. Now,...

Universal portfolio, part 7

July 7, 2012
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After reproducing all original figures and tables from Universal Portfolios, R coupled with modern processors allows to perform some more analysis.First we calculate the final wealth of the universal portfolio for all possible pairs of stocks, and...

SMS analysis (coming from an Android smartphone or an IPhone)

July 7, 2012
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At first, this post was intended to describe how to manipulate dates with R but, as the idea was coming from the question of one of my students who wanted to analyze his SMS, I thought that I might as well also explain the whole analysis process... Using my new smartphone (that I started to

The Actuary Puzzle 508 – Square numbers

The Actuary Puzzle 508 - Square numbers Author: Matt Malin From the puzzle pages of The Actuary June 2012, I attempt to solve the following, making use of R: This square contains exactly 21 smaller squares. Each of these smaller squares has sides of integer length, with no two smaller squares having sides of the same length. Can you find a solution for...

Timeline graph with ggplot2

July 7, 2012
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This post shows how to create a timeline graph by using ggplot2. Let’s start by loading the ggplot2 library. Next let’s create a dataset which we will use to feed the graph. In the last column (y), I create random positive values for the first three rows (which will be  Read more...

Graphical insights from the 2012 UseR! Meeting

About this time last month, I attended the 2012 UseR! Meeting.  Now an annual event, this series of conferences started in Europe in 2004 as an every-other-year gathering that now seems to alternate between the U.S. and Europe.  This year’s meeting was held on the VanderbiltUniversity campus in Nashville, TN, and it was attended by about 500 R aficionados,...

R, knitr & markdown = HTML

July 7, 2012
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Welcome to this demo of how R code and results can be combined into an HTML report. This entire blogpost was generated by using a combination of R, knitr and markdown. Beforehand, make sure you have the following libraries installed (latest version); knitr markdown ggplot2 (to run the example script)  Read more »

Project Euler — problem 12

July 7, 2012
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Going to supper in 20 minutes. I’d like to type down my solution to the 12th Euler problem, just make my time count. The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number … Continue reading →