Estimation of hydraulic conductivity and its uncertainty from grain-size data using GLUE and artificial neural networks.

June 13, 2012
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Estimation of hydraulic conductivity and its uncertainty from grain-size data using GLUE and artificial neural networks.

AbstractVarious approaches exist to relate saturated hydraulic conductivity (Ks) to grain-size data. Most methods use a single grain-size parameter and hence omit the information encompassed by the entire grain-size distribution. This study compares two data-driven modelling methods—multiple linear regression and artificial neural networks—that use the entire grain-size distribution data as input for Ks prediction. Besides the predictive capacity of the methods,...

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Comparing continuous distributions with R

June 13, 2012
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Comparing continuous distributions with R

In R we’ll generate similar continuous distributions for two groups and give a brief overview of statistical tests and visualizations to compare the groups. Though the fake data are normally distributed, we use methods for various kinds of continuous distributions. … Continue reading →

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In case you missed it: May 2012 Roundup

June 13, 2012
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In case you missed them, here are some articles from May of particular interest to R users. R tops the annual KDNuggets Data Mining Software poll for the first time. R 2.15.1 is scheduled for June 22. (Revolution R Enterprise 6, released on June 5, is based on 2.14.2.) A tutorial uses R, Hadoop, and the RHadoop project to...

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How to order bars in bar graph (Stack Overflow FAQ)

June 13, 2012
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How to order bars in bar graph (Stack Overflow FAQ)

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Why R is Hard to Learn

June 13, 2012
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Why R is Hard to Learn

The open source R software for analytics has a reputation for being hard to learn. It certainly can be, especially for people who are already familiar with similar packages such as SAS, SPSS or Stata. Training and documentation that leverages … Continue reading →

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Data on GitHub: The easy way to make your data available

June 13, 2012
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Data on GitHub: The easy way to make your data available

GitHub is designed for collaborating on coding projects. Nonetheless, it is also a potentially great resource for researchers to make their data publicly available. Specifically you can use it to:store data in the cloud for future use (for free),track ...

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Twitter unfollowers with R and Rook

Twitter unfollowers with R and Rook

In my last blog I'm following you in Twitter...are you following me back? I show you how to use the Twitter APIs to get a list of the people that you follow but doesn't follow you back.This time, I want to extend the tool as I installed the R...

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Next R meeting in Paris INSEE: ggplot2 and parallel computing

June 12, 2012
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Next R meeting in Paris INSEE: ggplot2 and parallel computing

Hi, our group of R users from INSEE, aka FLR, meets monthly in Paris. Next meeting is on Wed 13 (tomorrow), 1-2 pm, room 539 (an ID is needed to come in,  map to access INSEE R), about ggplot2 and parallel computing. Since the first meeting in February, presentations have included hot topics like webscrapping, C in R, RStudio, SQLite

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Finding word use patterns in Wikileaks cables

June 12, 2012
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Finding word use patterns in Wikileaks cables

6/18: A follow-up to this post is now available here.Recent DiscoveriesWhen I was a diplomat, I was always interested in the Wikileaks cables and what could be done with them. Unfortunately, I never got a chance to look at the site in depth, due to security policies. Now that the ex- is firmly prepended to diplomat...

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NBA Predictions — Finals

June 12, 2012
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NBA Predictions — Finals

Now we are on to the finals! The algorithm enters the finals with a 6-4 record so far. Here is what we have for tonight: So, let’s see if OKC wins this one.

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Twotorials

June 12, 2012
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Twotorials

http://www.twotorials.com/Heres a fun little page!About 90 two minute tutorials (twotorials, haha) on various things in R!From "what does object oriented programming mean" to calculating the number of days youve been alive.The guy has an amusing voice too!!Great for newbies to R I should imagine!!!Have a look!!

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PCA and ggplot2 to recognise gestures (via David…

June 12, 2012
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PCA and ggplot2 to recognise gestures (via David…

PCA and ggplot2 to recognise gestures (via David Chudzicki’s Blog: Visualizing ChaLearn Gestures Test Data)

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Interactive slideshows with R & Tiki (jquery.s5 powered)

June 12, 2012
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Interactive slideshows with R & Tiki (jquery.s5 powered)

Using PluginR you can produce interactive slideshows in Tiki running R code in some slides. This is possible thanks to the integrated jquery.s5 slideshow system, which was introduced already back in Tiki 7.0 and improved until its present form in Tiki...

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Density Estimation of High-Frequency Financial Data

Frequently we will want to estimate the empirical probability density function of real-world data and compare it to the theoretical density from one or more probability distributions. The following example shows the empirical and theoretical normal density for EUR/USD high-frequency … Continue reading →

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Quickly use googleVis in web reports using Tiki and PluginR

June 12, 2012
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Quickly use googleVis in web reports using Tiki and PluginR

R is hot and amazing. Tiki is too And with PluginR, we can easily place in simple or advanced web reports any R code, in a similar fashin to what can be achieved with other longer combinations (Sweave, Knitr, ... and latex). For instance, I tried a few days ago to quickly...

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Videos from ‘Tiki + PluginR’ workshop available

June 12, 2012
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Videos from ‘Tiki + PluginR’ workshop available

The videos from 'Tiki + PluginR' workshop given in Madrid (Nov'12) in the context of the "3as Jornadas de Usuarios de R en Castellano" are available online. See it within the page of the fulll workshop: 2011. Taller 5: Crea interfaces Web 2.0 a tus programas en R con software libre (LAMP + Tiki + PluginR)....

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Project Euler — problem 9

June 12, 2012
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Just had supper. My stomach is full of cabbage, carrot and noodle. I’d like to solve the ninth problem to stretch my mind. This one is about Pythagorean theorem. A Pythagorean triplet is a set of three natural numbers, a < b < … Continue reading →

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Simple network diagrams in R

June 12, 2012
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Simple network diagrams in R

Why study networks? Development and aid projects these days are more and more often focussing on supporting networks, so tools to analyse networks are always welcome. In this post I am going to present a very easy-to-use package for the stat...

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PluginR minor update with icon path fixed for Tiki9

June 12, 2012
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In Tiki9 icons and some other image paths have been refactored to share a common base folder. PluginR up to version 0.73 was using only paths from Tiki up to Tiki8. PluginR version 0.74 includes the icon also in the new path, so that it can be insta...

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Visualizing Euro 2012: First Group Games

June 12, 2012
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Visualizing Euro 2012: First Group Games

Now that every team has played a match it will be interesting to see how this has affected the (inverse) odds of victory. Since the plot in my last post was a bit ‘busy’, I have decided to use the facet_wrap function in gglplot2 to stratify by group. Also, re-producing the ‘busy’ plot from the

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First post…

June 12, 2012
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First post…

This is our first post of a series of posts that we plan to post here every now and then about our musings on R. What we use it for, new R packages that we discover, the power of using Tiki & PluginR in conjunction with R to produce web 2.0 reports using R's power in the backend and...

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An easy way to manage your genome-wide-association data: GenABEL package.

June 12, 2012
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Here is a little overview on GenABEL library developed by Yurii Aulchenko (www.genabel.org/). GenABEL is a full-featured R library for dealing with Genome-Wide Association analysis of binary and quantitative traits. Compared to the ‘genetics’ package and many other tools, GenABEL … Continue reading →

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Statistics of Drawdown–paper and post

June 11, 2012
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Statistics of Drawdown–paper and post

Thank so much to Patrick Burns’ post Variability in maximum drawdown.  He starts with “Maximum drawdown is blazingly variable,” which I say is why money management is so blazingly difficult.  After spending a lot of time thinking about ...

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Volatility Position Sizing 2

June 11, 2012
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Volatility Position Sizing 2

I have discussed Volatility Position Sizing in the Volatility Position Sizing to improve Risk Adjusted Performance post using the Average True Range (ATR) as a measure of Volatility. Today I want show how to use historical volatility to adjust portfolio leverage. Let’s start with Buy and Hold strategy using SPY and rescale it to the

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How to outrun a crashing alien spaceship

June 11, 2012
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How to outrun a crashing alien spaceship

Hollywood movies are obsessed with outrunning explosions and outrunning crashing alien spaceships. For explosions the movies give the optimal (but unusable) solution: run straight away. For crashing alien spaceships they give the same advice, but in this case it is wrong. We demonstrate the correct angle to flee. Running from a crashing alien spaceship, Prometheus Related posts:

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Transforming subsets of data in R with by, ddply and data.table

June 11, 2012
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Transforming subsets of data in R with by, ddply and data.table

Transforming data sets with R is usually the starting point of my data analysis work. Here is a scenario which comes up from time to time: transform subsets of a data frame, based on context given in one or a combination of columns.As an example I use ...

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\verbatim [beamer package]

June 11, 2012
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\verbatim [beamer package]

Once again working on my slides for the AMSI Lecture 2012 tour, it took me a while to get the following LaTeX code (about the family reunion puzzle) to work: \begin{frame} \slidetitle{A family meeting} \begin{block}{Random switch of couples} \only<1>{ \begin{itemize} \item Pick two couples at random with probabilities proportional to the

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Should I adjust the slope?

June 11, 2012
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Should I adjust the slope?

I add a new video “Should I adjust the slope”, where a new part of script is added to the monitor function.  I don´t recommend adjusting the slope, but there are circumstances where it is necessary:Suppose you have an equation, but not the ca...

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Do you still have time to sleep ?

June 11, 2012
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Do you still have time to sleep ?

Last week, @3wen (Ewen) helped me to write nice R functions to extract tweets in R and build datasets containing a lot of information. I've tried a couple of time on my own. Once on tweet contents, but it was not convincing and once on the activit...

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