R code for p curves

March 14, 2012
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I have finally got around to posting the R code for my p curve simulation. Those familiar with R will realize how crude it is (I've been caught up with other urgent stuff and had no time to explore further).You are welcome to play with (and improve!) t...

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Portfolio Optimization: Specify constraints with GNU MathProg language

March 14, 2012
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Portfolio Optimization: Specify constraints with GNU MathProg language

I have previously described a few examples of portfolio construction: Introduction to Asset Allocation Maximum Loss and Mean-Absolute Deviation risk measures 130/30 Portfolio Construction Minimum Investment and Number of Assets Portfolio Cardinality Constraints Multiple Factor Model – Building 130/30 Index (Update) I created a number of helper functions to simplify process of making the constraints(

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Scales and transformations in ggplot2 0.9.0

March 14, 2012
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Scales and transformations in ggplot2 0.9.0

Some R code designed for ggplot2 0.8.9 is not compatible with ggplot2 0.9.0, and today the ggplot2 web site has outdated documentation which gives this broken example: Dennis Murphy points to the ggplot2 0.9.0 transition guide from where I derived … Continue reading →

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NIT: Fatty acids study in R – Part 007

March 14, 2012
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NIT: Fatty acids study in R – Part 007

Once we have chosen the model, we can continue acquiring spectra of new samples. Spectra is exported to a txt or csv file and we imported in R to be reprocessed.We use the function “predict” from the PLS package. I have done this with 20 new sample...

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Creating a Stratified Random Sample of a Dataframe

March 14, 2012
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Creating a Stratified Random Sample of a Dataframe

Expanding on a question on Stack Overflow I'll show how to make a stratified random sample of a certain size: d <- expand.grid(id = 1:35000, stratum = letters)p = 0.1dsample <- data.frame()system.time(for(i in levels(d$stratum)) { dsub <...

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Video Tip: Convert Gene IDs with Biomart

March 14, 2012
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I get asked frequently how to convert from one gene identifier to another. This can be tricky, especially when relying on gene symbols, as Will pointed out in a previous post a few years ago. There are several tools that can do this, including DAVID an...

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March Madness! Wanna Win?

March 14, 2012
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March Madness! Wanna Win?

Description: Winning percentage of all NCAA Men's Basketball Tournament Champions. Analysis: Down by one, the ball spins in his hand as he dribbles up the floor. With tennis shoes squeaking, he feints left, then right. Glancing up at the clock,...

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π Day Special! Estimating π using Monte Carlo

March 14, 2012
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π Day Special! Estimating π using Monte Carlo

In honour of π day (03.14 – can’t wait until 2015~) , I thought I’d share this little script I wrote a while back for an introductory lesson I gave on using Monte Carlo methods for integration. The concept is simple – we can estimate the area of an object which is inside another object

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Visualising F1 Telemetry Data and Plotting Latitude and Longitude with ggplot Map Projections in R

March 14, 2012
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Visualising F1 Telemetry Data and Plotting Latitude and Longitude with ggplot Map Projections in R

Why don’t X-Y plots of latitude and longitude data look “right” compared to traditional map views? For example, here’s an X-Y scatterplot of some of Jenson Button’s McLaren telemetry data from the 2010 Australian Formula One Grand Prix: The image was generated, from a data file hosted on Google Spreadsheets, using the following R script,

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A ridiculous proof of concept: xyz interpolation

March 14, 2012
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A ridiculous proof of concept: xyz interpolation

Ridiculous OrbThis is really the last one on this theme for a while... I had alluded to a combination of methods regarding xyz interpolation at the end of my last post and wanted to demonstrate this in a final example.The ridiculousness that you see above involved two interpolation steps. First,...

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How to convert contingency tables to data frames with R

March 14, 2012
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I wanted to write contingency tables in HTML with hwrite(). I realized that the method hwrite() does not exist for the table objects. I could use as.data.frame(), but the table produced is non-intuitive. I did a search on R-bloggers and I quickly found the solution to my problem: the as.data.frame.matrix() function. The contingency table A

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ThinkStats … in R :: Example/Chapter 2 :: Example 2.1-2.3

March 14, 2012
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ThinkStats … in R :: Example/Chapter 2 :: Example 2.1-2.3

As promised, this post is a bit more graphical, but I feel the need to stress the importance of the first few points in chapter 2 of the book (i.e. the difference between mean and average and why variance is meaningful). These are fundamental concepts for future work. The “pumpkin” example (2.1) gives us an

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Simple plots reveal interesting artifacts

March 14, 2012
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Simple plots reveal interesting artifacts

I’ve recently been working with methylation data; specifically, from the Illumina Infinium HumanMethylation450 bead chip. It’s a rather complex array which uses two types of probes to determine the methylation state of DNA at ~ 485 000 sites in the genome. The Bioconductor project has risen to the challenge with a (somewhat bewildering) variety of

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More Anthromes !

March 13, 2012
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More Anthromes !

First off let me thank folks for all the comments and suggestions. I’m just starting to explore this data so perhaps I should explain how I go about  doing this. First off, I am looking for a global bias in the record from UHI. It is well known that you can look through the data

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Japan Trade More Specifically with Korea

March 13, 2012
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Japan Trade More Specifically with Korea

Macro analysis of Japanese trade in posts Japanese Trade and the Yen and Japan Trade by Geographic Region revealed some very interesting changes.  Since the Korean Won is so undervalued versus the Japanese Yen on a Purchasing Power Parity (PPP) ba...

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Plotting forecast() objects in ggplot part 1: Extracting the Data

March 13, 2012
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Lately I've been using Rob J Hyndman's excellent forecast package. The package comes with some built in plotting functions but I found I wanted to customize and make my own plots in ggplot. In order to do that, I need a generalizable function that will...

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Plotting forecast() objects in ggplot part 1: Extracting the Data

March 13, 2012
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Lately I've been using Rob J Hyndman's excellent forecast package. The package comes with some built in plotting functions but I found I wanted to customize and make my own plots in ggplot. In order to do that, I need a generalizable function that will...

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SNA with R workshop at Sunbelt XXXII in Redondo Beach

March 13, 2012
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SNA with R workshop at Sunbelt XXXII in Redondo Beach

I am currently in Redondo Beach, CA at the Sunbelt XXXII social networks conference. The program is thick from numerous interesting talks so the event promises to be very interesting. Today in the morning I gave the workshop “Introduction to Social Network Analysis with R”. Over 50 people registered. I am grateful to all the

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Scatter Plot Matrix in R

March 13, 2012
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Stata has a large number of graphics capabilities (and I highly recommend Stata over other statistical packages for a variety of reasons), but in a few instances R is more useful. In particular, I find R useful for creating beautiful scatter plot ...

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Shapley-Shubik Power Index in R

March 13, 2012
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Shapley-Shubik Power Index in R

This spring we have Rector Elections at Warsaw School of Economics. One of my collegues Tomasz Szapiro agreed to start in the elections. This induced me to write Shapley-Shubik Power Index calculation snippet in R.Rector elections in Warsaw School...

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Video: Using R in Academic Finance

March 13, 2012
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The slides and replay for Dr Sanjiv Das's webinar, Using R for Analyzing Loans, Portfolios and Risk: From Academic Theory to Financial Practice are now available. I've embedded the slides below: they tell a great story of how Das, after being mistaken for the then-CEO of Citibank (with whom he shares a name) was then led to research (using...

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R-Function to Read Data from Google Docs Spreadsheets

March 13, 2012
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R-Function to Read Data from Google Docs Spreadsheets

I used this idea posted on Stack Overflow to plug together a function for reading data from Google Docs spreadsheets into R. google_ss <- function(gid = NA, key = NA) { if (is.na(gid)) {stop("\nWorksheetnumber (gid) is missing\n")} if (is....

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Oracle R Distribution and Open Source R

March 13, 2012
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Oracle provides the Oracle R Distribution, an Oracle-supported distribution of open source R. Support for Oracle R Distribution is provided to customers of the Oracle Advanced Analytics option and the Oracle Big Data Appliance. The Oracle R Distribu...

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R code for Chapter 2 of Non-Life Insurance Pricing with GLM

March 13, 2012
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R code for Chapter 2 of Non-Life Insurance Pricing with GLM

We continue working our way through the examples, case studies, and exercises of what is affectionately known here as “the two bears book” (Swedish björn = bear) and more formally as Non-Life Insurance Pricing with Generalized Linear Models by Esbjörn Ohlsson and Börn Johansson (Amazon UK | US

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R code for Chapter 2 of Non-Life Insurance Pricing with GLM

March 13, 2012
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R code for Chapter 2 of Non-Life Insurance Pricing with GLM

We continue working our way through the examples, case studies, and exercises of what is affectionately known here as “the two bears book” (Swedish björn = bear) and more formally as Non-Life Insurance Pricing with Generalized Linear Models by Esbjörn Ohlsson and Börn Johansson (Amazon UK | US). At...

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In case you missed it: February Roundup

March 13, 2012
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In case you missed them, here are some articles from February of particular interest to R users. February 29 marked the 12th anniversary of the release of R 1.0.0, and the release of R 2.14.2. A list of commercial vendors who have integrated R with their products for data, analysis, and presentation. The rmr package (part of the RHadoop...

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Data Science – learn the lessons of software

March 13, 2012
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We're starting to see a deluge of companies who businesses are all about making data analysis/science/insight "easy for the non-expert". We've been here before, quite a few times sadly. When I started writing software 12 years ago, there was...

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Example 9.23: Demonstrating proportional hazards

March 13, 2012
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Example 9.23: Demonstrating proportional hazards

A colleague recently asked after a slide suitable for explaining proportional hazards. In particular, she was concerned that her audience not focus on the time to event or probability of the event. An initial thought was to display the cumulative haz...

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Anthromes and UHI

March 12, 2012
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Anthromes and UHI

With BerkeleyEarth 1.6 posted to CRAN I figured it was time to do some sample programs to explain how the package worked and integrated with other packages. Also, I have some issues to check out with the metadata; and in the long run I want to reformulate my metadata package to include some new resources.

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