March 2009

Andrews’ Curve And Parallel Coordinate Graph

March 11, 2009 | 0 Comments

Unison graph and parallel coordinate graph share similar thought in visualising the difference of multidimensional data, thought the former is much more complicated. Based on iris data, we can see their performance.Parallel coordinate graphAndrews' Cur... [Read more...]

Scatterplots

March 11, 2009 | 0 Comments

There are many types of scatterplots in R, here are some examples based on the famous Iris data.pairs() and coplot() in package graphics.gpairs() in package YaleToolkit.scatterplot.matrix() or spm() in package car.splom() in package lattice. [Read more...]

Choosing an SQL Engine for Analytics

March 9, 2009 | 0 Comments

I’ve been struggling for a while on which database to use for my working data. I used to use MS Access quite a lot. The problems with MS Access include but are not limited to: 2 GB file size limit, at least historically Versions change with each edition of MS ...
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Repeated Measures ANOVA using R

March 9, 2009 | 0 Comments

While so-called “between-subjects” ANOVA is absolutely straightforward in R, performing repeated measures (within-subjects) ANOVA is not so obvious. I have come across at least three different ways of performing repeated measures ANOVA in R. Which method you use depends on … Continue reading → [Read more...]

i-Screen, u-Screen, Vee All Screen for Which Screen?

March 9, 2009 | 0 Comments

When I first came to the USA, it quickly became apparent that there was no such thing as, ice cream. You had to specify what flavor, what combination of flavors, what kind of cone, what you wanted on top of it, and so on. This is all enshrined in the ...
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NREGA and Indian maps in R

March 8, 2009 | 0 Comments

A few days ago I was reading an article by Jean Drèze and his colleagues on how the first two years of National Rural Employment Guarantee Act (NREGA) has progressed (There was another article by Drèze on NREGA in 2007). The NREGA is empowering the rural people in a ... [Read more...]

Coimbatore Weather and Questioning Amma!

March 8, 2009 | 0 Comments

A week ago, Amma was telling the weather was getting hot in Coimbatore. I was telling her it is going to get worse in the next two months. She shot back saying that March is the hottest month while April and May are less hotter in Coimbatore. Growing up in ... [Read more...]

Dealing with missing values

March 8, 2009 | 0 Comments

Two new quick tips from 'almost regular' contributor Jason: Handling missing values in R can be tricky. Let's say you have a table with missing values you'd like to read from disk. Reading in the table with, read.table( fileName ) might fail. If ...
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So here we have our 1st problem…

March 7, 2009 | 0 Comments

Hey all of you,I got such an interesting problem, a friend of mine is modelling something using bayesian statistics and she got an equation system to solve, but she's stucked and she showed to me such a long script to ty to solve it with numeric approx... [Read more...]

Hello everybody

March 7, 2009 | 0 Comments

Well... I don’t really know what to write, but Iknow that I want to say ‘Welcome’ to all of you who are checking this blog, I’m a student, majoring in Actuarial Science in Mexico city, and I thought about a place where we could share ideas and knowledge ... [Read more...]

Causation’s Mistreated Sibling Correlation

March 6, 2009 | 0 Comments

This is why I love XKCD, though surely the best part of this strip was the mouseover: “correlation doesn’t imply causation, but it does waggle its eyebrows suggestively and gesture furtively while mouthing, ‘look over there’.”
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Workflow with Python and R

March 6, 2009 | 0 Comments

I seem to be doing more and more with Python for work over and above using it as a generic scripting language. R has been my workhorse for analysis for a long time (15+ years in various incarnations of S+ and R), but it still has some deficiencies. I’m finding ...
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Short introduction to R in Finance

March 5, 2009 | 0 Comments

Adam Gehr of DePaul University's Finance Department had organized a panel session about R in Finance at the Midwest Finance Association's 58th Annual Meeting which is happening this week here in Chicago. I just posted my slides on my presentations page. The slides give a brief overview of R, the ... [Read more...]

R User Group Meeting, London

March 5, 2009 | 0 Comments

On Tuesday March 31st, Mango Solutions are sponsoring the inaugural London R User Group Meeting. It will be a great opportunity to meet other R users and find out how people are using it. As the first one of its kind in London, I would expect a high le... [Read more...]

Wanderlust

March 4, 2009 | 0 Comments

We Americans have a reputation as being unworldly. Given the results of the most recent Pew survey, perhaps we deserve it. Evidently, the majority of us never move out of our home states. [Read more...]

Click Tracks and Beat Detection

March 4, 2009 | 0 Comments

Being a drummer, a programmer and a fan of statistical analysis, this post on the (unnaturally) perfect timing of drum parts recorded to a click track was a real delight to me. Of course, many claims in the post are odd: it seems hard to imagine that a... [Read more...]

RQuantLib 0.2.11

March 3, 2009 | 0 Comments

The changes in Rcpp that I blogged about a few days ago required a few small changes in RQuantLib. Not really much more that prefixing std:: in a number of variable declarations and a few member function calls -- so this is definitely a minor maintenance release. New source and ... [Read more...]

Simulate parameters of a tobit model

March 3, 2009 | 0 Comments

I got an email, asking me if our arm package can simulate tobit model to get simulated parameters. Indeed, arm does not suport tobit model. It only support sim() for lm, glm and mer classes in R. But it is not difficult to get a tobit verison of sim(). Here ... [Read more...]

Project Euler Problem #28

March 2, 2009 | 0 Comments

Problem 28 on the Project Euler website asks what is the sum of both diagonals in a 1001×1001 clockwise spiral. This was an interesting one: the relationship between the numbers on the diagonals is easy to deduce, but expressing it succinctly in R... [Read more...]

Color Schemes for R Bar Plots

March 1, 2009 | 0 Comments

A recurrent source of irritation for me is the absence of a good default behavior in R for choosing the color scheme for bar plots. A stacked bar plot looks only as good as the color scheme you use. In hope of finding a usable scheme that I could settl...
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