Liking of apples – more than juiciness

March 18, 2012
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Liking of apples – more than juiciness

In a previous blog it was shown using literature data that liking of apples was related to juiciness. However, there were some questionsIs the relation linear or slightly curved? The variation in liking around CJuiciness is large. Are more explana...

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Useful R snippets

March 18, 2012
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Useful R snippets

In this post we collect several R one- or few-liners that we consider useful. As our minds tend to forget these little fragments we jot them down here so we will find them again. Indexing in nested loops Every once in a while I run a nested loop like the following one. Now if I

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How to read an excel file (dot xls and dot xlsx) into a data frame with r

March 17, 2012
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How to read an excel file (dot xls and dot xlsx) into a data frame with r

how to read an excel file (dot xls and dot xlsx) into a data frame with r

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Predicting Marketing Campaign with R

March 17, 2012
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Predicting Marketing Campaign with R

In my last blog I created a mechanism to fetch data from Salesforce using rJava and SOQL. In this blog I am going to use that mechanism to fetch ad campaign data from salesforce and predict future ad campaign sales using R Let us assume that Salesforce has campaign data for last eight quarters.  This

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Logistic map: Feigenbaum diagram

March 17, 2012
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Logistic map: Feigenbaum diagram

The other day I found some old basic code I had written about 15 years ago on a Mac Classic II to plot the Feigenbaum diagram for the logistic map. I remember, it took the little computer the whole night to produce the chart.With today's computers even...

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Solving easy problems the hard way

March 17, 2012
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Solving easy problems the hard way

There’s a charming little brain teaser that’s going around the Interwebs. It’s got various forms, but they all look something like this: This problem can be solved by pre-school children in 5-10 minutes, by programer – in 1 hour, by people with higher education … well, check it yourself!  8809=6 7111=0 2172=0 6666=4 1111=0 3213=0 7662=2 9313=1 0000=4 2222=0 3333=0 5555=0 8193=3 8096=5 7777=0 9999=4 7756=1 6855=3 9881=5 5531=0 2581=? SPOILER ALERT… The answer has to do with how many

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Savitzky-Golay filters in R

March 17, 2012
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Savitzky-Golay filters in R

Derivatives are a good way to extract information to our spectra. As we know NIR contents overlapping bands, and spectra must be treated with math operations in order to extract as much information as possible and to correlate it with the constituent &...

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Cooling Stations

March 17, 2012
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Cooling Stations

Over the course of the past few years I have taking a look at cooling stations a few times but never in much depth. A few other people have looked at them, but usually without much rigor. The standard approach is to find some cooling stations and then conclude that somehow global warming is thereby

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Dates and times in R

March 16, 2012
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Nothing looks funnier than a patchy simian. That's why we sighed a great sigh of relief when we spotted this article on the lubridate package in R. It saves a great deal of hair pulling.http://www.r-statistics.com/2012/03/do-more-with-dates-and-times...

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simulated annealing for Sudokus [2]

March 16, 2012
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simulated annealing for Sudokus [2]

On Tuesday, Eric Chi and Kenneth Lange arXived a paper on a comparison of numerical techniques for solving sudokus. (The very Kenneth Lange who wrote this fantastic book on numerical analysis.) One of these techniques is the simulated annealing approach I had played with a long while ago.  They seem to use the same penalisation

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Simplify working with times and dates in R

March 16, 2012
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R has some very powerful built-in features for working with dates, times, and time-zones. But power and flexibility rarely correlate with ease-of-use, and this is no exception. The lubridate package comes to the rescue, make things a bit easier when working with chronological data in R. The paper Dates and Times Made Easy with lubridate provides in-depth explanations of...

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Montreal R Workshop: Likelihood Methods and Model Selection

March 16, 2012
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Montreal R Workshop: Likelihood Methods and Model Selection

Monday, March 19, 2012  14h-16h, Stewart Biology N4/17 Corey Chivers, McGill University Department of Biology This workshop will introduce participants to the likelihood principal and its utility in statistical inference.  By learning how to formalize models through their likelihood function, participants will learn how to confront these models with data in order to make statistical

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Download and Parse DJ/UBS Commodities Indexes

March 16, 2012
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Download and Parse DJ/UBS Commodities Indexes

Here is another data downloading and parsing script, this one for the Dow Jones/UBS Commodities Indexes. Compared to the last post, this parser deals with multiple sheets and multiple columns in each sheet. It also constructs monthly series from the daily data, and stores it using a different symbol. Finally, it’s a good example of

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Do more with dates and times in R with lubridate 1.1.0

March 16, 2012
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This is a guest post by Garrett Grolemund (mentored by Hadley Wickham) Lubridate is an R package that makes it easier to work with dates and times. The newest release of lubridate (v 1.1.0) comes with even more tools and …Read more »

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digest 0.5.2

March 15, 2012
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A new version of the digest package (which generates hash function summaries for arbitrary (and possibly nested) R objects using any of the standard md5, sha-1, sha-256 or crc32 algorithms) is now on CRAN. Murray Stokely noticed a corner case where...

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A No BS Guide to the Basics of Parallelization in R

March 15, 2012
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What is parallelization?Parallelization is using multiple processing cores to, hopefully, make your programs run faster than serial code, which is the use of just one processing core. Parallel code is not always faster than its serial counterpart (but if you're doing it right and you're careful about what you parallelize, it will be --- remember, that's your goal here). ...

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p curves revisited

March 15, 2012
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I finally found some time to take a closer look at p curves. I haven't had a chance to follow-up my simulations (and probably won't for a few weeks if not months), but I have had time to think through the ideas the p curve approach raises based on some of the comments I've received and a brief exchange...

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R gotcha for the week

March 15, 2012
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R gotcha for the week

I use the biomaRt package from Bioconductor in almost every R session. So I thought I’d load the library and set up a mart instance in my ~/.Rprofile: On starting R, I was somewhat perplexed to see this error message: Twitter to the rescue. @hadleywickham told me to load utils first and @vsbuffalo explained that

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Europe most dangerous cities

March 15, 2012
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Europe most dangerous cities

When I was searching for data about U.S prison population, for another post, I run across eurostat, a nice source for data to play around with. I pooled some numbers, specifically homicides recorded by the police. A panel data for … Continue reading →

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SAP integrates R with HANA

March 15, 2012
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SAP integrates R with HANA

We can add SAP to the list of vendors offering R integration with their products. InformationWeek reports that the new SAP BusinessObjects Predictive Analysis model provides a graphical user interface to R. Created in reaction to "competitive and market forces, including the momentum of open source R", the new module provides in-database processing (presumably by embedding R within HANA...

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Liking of apples – some data to link

March 15, 2012
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Liking of apples – some data to link

I browsed through a paper by Peneau et al. (J. Sensory Studies, 2007) where they have nice data on apples; consumer evaluation, sensory evaluation and instrumental measurements. I think these are interesting data to examine if these variable blocks can...

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The Anachronism Machine: The Language of Downton Abbey

March 15, 2012
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The Anachronism Machine: The Language of Downton Abbey

I've recently become hooked on the TV series Downton Abbey. I'm not usually one for costume dramas, but the mix of fine acting, the intriguing social relationships, and the larger WW1-era story make for compelling viewing. (Also: Maggie Smith is a treasure.) Despite the widespread criticial acclaim, Downton has met with criticism for some period-innapropriate uses of language. For...

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Opinions Not Backed by Money Updated Again

March 15, 2012
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Opinions Not Backed by Money Updated Again

Strange that I am updating this post for a third time and nothing really has changed, but the fact that nothing has changed is incredibly interesting to me.  Since it is an update, I will not duplicate the explanation, so please read the last vers...

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A Graphical Explanation of how to Interpret a Dendrogram

March 15, 2012
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A Graphical Explanation of how to Interpret a Dendrogram

Dendrograms are a convenient way of depicting pair-wise dissimilarity between objects, commonly associated with the topic of cluster analysis. This is a complex subject that is best left to experts and textbooks, so I won't even attempt to cover it her...

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New R User Group in Montreal

March 15, 2012
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New R User Group in Montreal

The Montreal R User Group is now official. You can join the group by visiting the meetup site. The group has existed since 2010 in a narrower incarnation as the BGSA R/Stats Workshop Series. Previous workshops have featured invited facilitators on topics such as Causal Analysis, GLMs, GAMs, Multi-model inference, Phylogenetic analysis, Bayesian modeling, Meta-analysis,

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Project Euler: Problem 16

March 15, 2012
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215 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.What is the sum of the digits of the number 21000?Handling large numbers or rather, very large numbers, can be a pain at times. But have no fear, for GMP is here.GMP  makes the s...

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Call for chapters: Data Mining Applications with R

March 15, 2012
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Call for chapters: Data Mining Applications with R

Data Mining Applications with R A book to be published by Elsevier http://www.RDataMining.com/books/book2 Proposal Submission Deadline: April 30, 2012 Introduction R is one of the most widely used data mining tools in scientific and business applications, among dozens of commercial … Continue reading →

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Ideas on A Really Fast Statistics Journal

March 15, 2012
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I was writing comments on the blog post A proposal for a really fast statistics journal, and I realized the comment box was too small to write down my ideas. I like the proposal a lot, and I feel really bad about the current model of submitting and rev...

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R and Hadoop: Step-by-step tutorials

March 14, 2012
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R and Hadoop: Step-by-step tutorials

At the recent Big Data Workshop held by the Boston Predictive Analytics group, airline analyst and R user Jeffrey Breen gave a step-by-step guide to setting up an R and Hadoop infrastructure. Firstly, as a local virtual instance of Hadoop with R, using VMWare and Cloudera's Hadoop Demo VM. (This is a great way to get familiar with Hadoop.)...

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