Geolocate IP addresses in R

May 20, 2013
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Geolocate IP addresses in R

This R function uses the free freegeoip.net geocoding service to resolve an IP address (or a vector of them) into country, region, city, zip, latitude, longitude, area and metro codes. Continue reading →

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R programming challenge: Escape the zombie horde

May 20, 2013
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R programming challenge: Escape the zombie horde

So when the world is taken over by a Zombie horde, you're going to want to figure out a way to get the human population to safety. This R script by econometrician Francis Smart won't help you do that exactly, but given a list of waypoints to navigate through zombie-infested lands to a safe house, it will tell you...

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Solving Multiple Supplier Selection Problem using R and LP Solve

May 20, 2013
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Solving Multiple Supplier Selection Problem using R and LP Solve

(This article was first published on Enterprise Software Doesn't Have to Suck, and kindly contributed to R-bloggers) To leave a comment for the author, please follow the link and comment on their blog: Enterprise Software Doesn't Have to Suck. R-bloggers.com offers daily e-mail updates about R news and tutorials on topics such as: Data science, Big Data, R jobs,...

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Non-Verbal Reasoning Test – Concerto

May 20, 2013
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Non-Verbal Reasoning Test – Concerto

I have just released my first complete test of non-verbal problem solving skills.  It is run on Concerto (an R-based application development platform targeted at primarily test developers)  Try it out by following the link below.Non-Verbal Re...

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R 3.0.1 is released

May 20, 2013
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R 3.0.1 is released

R 3.0.1 (codename “Good Sport”) was released last week. As mentioned earlier by David, this version improves serialization performance with big objects, improves reliability for parallel programming and fixes a few minor bugs. Upgrading to R 3.0.1 You can download …Read more »

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R/Finance 2013 slides

May 20, 2013
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R/Finance 2013 slides

I have just returned from the R/Finance conference and want to share with you my slides and examples. The Cluster Risk Parity portfolio allocation method is an example of Cluster Portfolio Allocation methods that focuses on diversification or more specifically diversification of your risk bets. (i.e. portfolio that distributes risk equally both within clusters and

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More on Chutes & Ladders

May 20, 2013
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More on Chutes & Ladders

Matt Maenner asked about the sawtooth pattern in the figure in my last post on Chutes & Ladders. Damn you, Matt! I thought I was done with this. Don’t feed my obsession. My response was that if the game ends early, it’s even more likely that it’ll be the kid who went first who won.

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Model fitting exam problem

May 20, 2013
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Recently I have run an exam where the following question had risen many problems for students (here I give its shortened formulation). You are given the data generating process y = 10x + e, where e is error term. Fit linear regression using lm, ne...

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qdap 0.2.2 released

May 20, 2013
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qdap 0.2.2 released

I’m very pleased to announce the release of qdap 0.2.2 This is the third installment of the qdap package available at CRAN. The qdap package automates many of the tasks associated with quantitative discourse analysis of transcripts containing discourse, including … Continue reading →

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Implied alpha and minimum variance

May 20, 2013
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Implied alpha and minimum variance

Under the covers of strange bedfellows. Previously The idea of implied alpha was introduced in “Implied alpha — almost wordless”. In a comment to that post Jeff noticed that the optimal portfolio given for the example is ever so close to the minimum variance portfolio.  That is because there is a problem with the example … Continue reading...

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analyze the new york city housing and vacancy survey (nychvs) with r

May 19, 2013
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for those interested in the real estate and rental markets of the big apple, the census bureau's nyc housing and vacancy survey might be your key to the city.  if you care about how many new york residents live more than one person per room (a lot...

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When Does the Kinetic Theory of Gases Fail? Examining its Postulates with Assistance from Simple Linear Regression in R

When Does the Kinetic Theory of Gases Fail?  Examining its Postulates with Assistance from Simple Linear Regression in R

Introduction The Ideal Gas Law, , is a very simple yet useful relationship that describes the behaviours of many gases pretty well in many situations.  It is “Ideal” because it makes some assumptions about gas particles that make the math and the physics easy to work with; in fact, the simplicity that arises from these

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Playing cards in Vegas?

May 19, 2013
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Playing cards in Vegas?

In a previous post, a few weeks ago, I mentioned that I will be in Las Vegas by the end of July. And I took the opportunity to write a post on roulette(s). Since some colleagues told me I should take some time to play poker there, I guess I have to understand how to play poker… so I...

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More tide prediction with R

May 19, 2013
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In the previous post I outlined how to query the XTide software with R and parse the results into a handy-dandy data frame. The biggest hurdle with that method is getting XTide up and running on your computer. The code outlined here works entirely within R, so you don’t need XTide installed on your computer.

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R code to obtain and plot rainfall data for the whole world

If you want to create rainfall maps for the whole world in R there is no readily available code or package to do this. Moreover, data publicly available from research institutions is not generally in plain text format or other familiar formats. Hydrological and climatological studies sometimes require rainfall data over the entire world for long periods of time....

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Exploratory Data Analysis – Computing Descriptive Statistics in R for Data on Ozone Pollution in New York City

Exploratory Data Analysis – Computing Descriptive Statistics in R for Data on Ozone Pollution in New York City

Introduction This is the first of a series of posts on exploratory data analysis (EDA).  This post will calculate the common summary statistics of a univariate continuous data set – the data on ozone pollution in New York City that is part of the built-in “airquality” data set in R.  This is a particularly good data set

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Update to PSID panel builder for R: psidR

May 19, 2013
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I just pushed the most recent version of the PSID panel data builder introduced a little while ago. Got some user feedback and made some improvements. The package is hosted on github.News:I added a reproducible example using artificial data which you c...

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Conversion between Factor and Dummies in R

May 18, 2013
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Conversion between Factor and Dummies in R

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Sharing my R notes

May 18, 2013
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Sharing my R notes

I started working with R 2 1/2 years ago. I remember opening R closing it and thinking it was the dumbest thing ever (command line to a non programmer is not inviting). Now it’s my constant friend. From the beginning … Continue reading →

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Using gdata, for MS Windows users

May 18, 2013
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Using gdata, for MS Windows users

I use both GNU-Linux and Windows systems on a regular basis… so I’m aware of the advantages (more for GNU-Linux in my case) and disadvantages of both. Recently I needed to analyse a database from a remote location, an Excel … Sigue leyendo →

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R (Web Server) Solutions – Amplifying Artichokes

May 18, 2013
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R (Web Server) Solutions – Amplifying Artichokes

Every month I see one or more new R based web server solutions coming into the market, sight seeing some of them thought of sharing one of my old architecture map manifested to the client long back in early 2009 (good to see quick spreading of scalable...

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What is probabilistic truth?

May 18, 2013
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What is probabilistic truth?

I am currently working on a validation metric for binary prediction models. That is, models which make predictions about outcomes that can take on either of two possible states (eg Dead/not dead, heads/tails, cat in picture/no cat in picture, etc.) The most commonly used metric for this class of models is AUC, which assesses the

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Recent Changes to caret

May 18, 2013
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Here is a summary of some recent changes to caret. Feature Updates: train was updated to utilize recent changes in the gbm package that allow for boosting with three or more classes (via the multinomial distribution) The Yeo-Johnson power transformation was added. This is very similar to the Box-Cox transformation, but it does not require the data to be...

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Mining the last French presidential debate

May 18, 2013
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Mining the last French presidential debate

After reading this post (thanks to him), I think it could be interesting to replicate this with some specific up of french language and to see and we can perform rapid view of the debate between Sarkozy and Hollande of the last 2nd round of presidentia...

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Bubble sort tuning

May 18, 2013
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I was reading Paul Hiemsta's blogpost on Much more efficient bubble sort in R using the Rcpp and inline packages, went back to his first post  Bubble sort implemented in pure R and thought, surely we can do it better in pure R. So I...

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Interfacing XTide and R

May 17, 2013
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XTide is an open-source program that predicts tide heights and current speeds for hundreds of tide and current stations around the United States. It can be used to produce tide predictions in the past and future for a site at your chosen interval (down...

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Unit conversion in R

May 17, 2013
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Last weekend I submitted an update of my R package datamart to CRAN. It has been more than a half year since the last update, however there are only minor advances. The package is still in its early stages, and very experimental.One new feature is the function uconv. Think iconv, but instead of converting character vectors between different encodings,...

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Chutes & ladders: How long is this going to take?

May 17, 2013
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Chutes & ladders: How long is this going to take?

I was playing Chutes & Ladders with my four-year-old daughter yesterday, and I thought, “How long is this going to take?” I saw an interesting mathematical analysis of the game a few years ago, but it seems to be offline, though you can read it via the wayback machine. But that didn’t answer my specific

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Which Torontonians Want a Casino? Survey Analysis Part 2

May 17, 2013
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Which Torontonians Want a Casino?  Survey Analysis Part 2

In my last post I said that I would try to investigate the question of who actually does want a casino, and whether place of residence is a factor in where they want the casino to be built.  So, here … Continue reading →

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