July 2012

Project Euler — problem 16

July 21, 2012 | Tony

The 16th problem is another big-number problem: 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? This … Continue reading → [Read more...]

Base versus grid graphics

July 21, 2012 | Ron Pearson (aka TheNoodleDoodler)

In a comment in response to my latest post, Robert Young took issue with my characterization of grid as an R graphics package. Perhaps grid is better described as a “graphics support package,” but my primary point – and the main point of this post – is that to generate the display ... [Read more...]

The magic of the year 1901

July 21, 2012 | Frans Slothouber

The year 1901 is rather magical. Well it is for R provided you run it under Linux. Let me show you why. I have four data points, one from 1900, two from 1901, and one from 1902. dates values I convert them in two different ways; as a Date, and as a POSIXct. For ... [Read more...]

googleVis — where did SYTYCD dancers come from?

July 21, 2012 | Tony

After watching 20 wonderful dancers of the 9th season of So You Think You Can Dance, I have presented a geomap of  the states where they are coming from (click here). Now, I am interested to this show’s history.  I’d like to re-draw the … Continue reading → [Read more...]

Automatic Hyperparameter Tuning Methods

July 20, 2012 | John Myles White

At MSR this week, we had two very good talks on algorithmic methods for tuning the hyperparameters of machine learning models. Selecting appropriate settings for hyperparameters is a constant problem in machine learning, which is somewhat surprising given how much expertise the machine learning community has in optimization theory. I ... [Read more...]

Le Monde puzzle [#783]

July 20, 2012 | xi'an

In a political party, there are as many cells as there are members and each member belongs to at least one cell. Each cell has five members and an arbitrary pair of cells only shares one member. How many members are there in this political party? Back to the mathematical ... [Read more...]

R Journal, June 2012

July 20, 2012 | David Smith

The June 2012 issue of the R Journal, the peer-reviewed open-journal about R packages and applications of R, is now available. This issue includes articles about: Efficiently calling C functions from R without the need for wrapper code Using clusters of Macs running Apple Xgrid for parallel distributed processing with R ... [Read more...]

Modeling Permanent and Gradual Process Changes with CDFs

July 20, 2012 | Spencer Herath

Spencer HerathSpecial thanks to Ben OgorekBackgroundI recently faced a process with a structural change resulting in an increase in the process mean.  The jump to the new mean was not immediate; rather, there was a gradual increase in values over time.  I had previously benefited from multi-staged process-behavior charts when ... [Read more...]

Look ma! No typing! Autorunning code on R startup

July 20, 2012 | richierocks

Regular readers may know that I often make R-based GUIs. They’re great for giving non-technical users safe and easy access to statistical models. The safety comes from the restrictions of a GUI: you can limit what the users does more easily than with a command line, helping to reduce ... [Read more...]

Time-based internet advertising

July 20, 2012 | dan

Last week it was announced that Facebook is rotating its ads after a certain time of exposure. Sid Suri, Preston McAfee, and Dan Goldstein's research may have been the source of this idea. In 2011 and 2012 the trio published a couple papers putting for and improving the idea. The post Time-based ... [Read more...]

Volatility and Correlation

July 19, 2012 | quantsignals

The implied option volatility reflects the price premium an option commands. A trader’s profit and loss ‘P&L’ from hedging option positions is driven to a large extend by the actual historical volatility of the underlying assets. Thus as option premiums … Continue reading → [Read more...]

Course at Monash (#2)

July 19, 2012 | xi'an

Here are the slides for the second day of my course at Monash University, Melbourne, in the Special Lectures in Econometrics, with a strong strong similarity with the slides of my course in Roma this Spring. (Ah, sunny Roma…) The first day lecture was very well attended and I hope ... [Read more...]

Best of Axys, R, d3.js, and HTML5

July 19, 2012 | klr

Axys, R, d3.js, and HTML5 all offer incredibly powerful tools for investment management and reporting, but they are not set up to synergistically interact to fill each other’s gaps and leverage each other’s strengths.  In my ideal scenario, Ax...
[Read more...]

Outer Product of Character Vectors in R

July 19, 2012 | Isomorphismes

What follows is like a kata to strengthen your R fundamentals. The lovely stats in the wild recently posted some hott data analysis of Olympians’ ages and sexes. Because I’m annoyingly picky about graphics, I asked for his code so I could ... [Read more...]

Random Forest Variable Importance

July 19, 2012 | Andrew Landgraf

Random forests ™ are great. They are one of the best "black-box" supervised learning methods. If you have lots of data and lots of predictor variables, you can do worse than random forests. They can deal with messy, real data. If there are lots of extraneous predictors, it has no problem. ... [Read more...]
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