I have programmed up a R based Sudoku problem solver for Sudoku puzzles of that only require simple inference. In these puzzles a solution can be found using only first order inference. This solver can be found at the end of the code locate...

I just stumbled across a really useful infix function in R: %in%. It compares two vectors and returs a logical vector if there is a match or not for its left operand. Let us look at some examples: > 1:10 %in% c(1,3,5,9) TRUE FALSE TRUE...

This afternoon I went to Max Kuhn’s tutorial on his caret package. caret stands for classification and regression (something beginning with e) trees. It provides a consistent interface to nearly 150 different models in R, in much the same way as the plyr package provides a consistent interface to the apply functions. The basic usage

I’m at user 2013, and this morning I attended Hadley Wickham and Romain Francois’s tutorial on the Rcpp package for calling C++ code from R. I’ve spent the last eight years avoiding C++ afer having nightmares about obscure pointer bugs, so I went into the room slightly skeptical about this package. I think the most

In a recent article at Statistics View, Lillian Pierson describes how the X+1 Origin Digital Marketing Hub helps companies like JP Morgan Chase and Verizon optimize their marketing efforts. Back in 2011, X+1 saw the need to update their analytics platform to deal with increasing data sizes and to serve the increasingly sophisticated needs of their marketing clients: What...

If Big Data was last year's buzzword, Data Science may reach the same level of hype this year. There's no shortage of discussion about the high demand for data scientists, the term's usefulness as a designation, and even declarations of its "sexiness" as a career. And as with many terms that reach a critical mass on social media, data...

R speeds up when the Basic Linear Algebra System (BLAS) it uses is well tuned. The reference BLAS that comes with R and Ubuntu isn't very fast. On my machine, it takes 9 minutes to run a well known R benchmarking script. If I use ATLAS, an optimized BLAS that can be easily installed, the

R speeds up when the Basic Linear Algebra System (BLAS) it uses is well tuned. The reference BLAS that comes with R and Ubuntu isn’t very fast. On my machine, it takes 9 minutes to run a well known R … Continue reading →

Introduction Continuing my recent series on exploratory data analysis (EDA), today’s post focuses on histograms, which are very useful plots for visualizing the distribution of a data set. I will discuss how histograms are constructed and use histograms to assess the distribution of the “Ozone” data from the built-in “airquality” data set in R. In

Most of time, I don’t need to deal with different encodings at all. When possible, I use ASCII characters. And when there is a little processing in Chinese characters or other Unicode characters, I use .Net languages or JVM languages, in which every string is Unicode and of course when the characters are displayed they are displayed as characters...

(This article was first published on Milano R net, and kindly contributed to R-bloggers) As mentioned in the previous article, a possibility for dealing with some Big Data problems is to integrate R within the Hadoop ecosystem. Therefore, it’s necessary to have a bridge between the two environments. It means that R should be capable of handling data the...

(This article was first published on Commodity Stat Arb, and kindly contributed to R-bloggers) I can’t believe it has been nearly 6 months since I last posted. Given the sustained heat it seemed like a good idea to finish off this subject. As hinted at in my last post, temperature is the missing variable to make sense of Residential...

the american time use survey collects information about how we spend our time. it's a pretty simple setup: sampled individuals write down everything they do for a single twenty-four hour period, in ten minute intervals. those diaries are a...

(This article was first published on Just Another R Blog, and kindly contributed to R-bloggers) To leave a comment for the author, please follow the link and comment on their blog: Just Another R Blog. R-bloggers.com offers daily e-mail updates about R news and tutorials on topics such as: Data science, Big Data, R jobs, visualization (ggplot2, Boxplots, maps,...

Heatmaps are a great way to visualize data matrices. Heatmap color and organization can be used to encode information about the data and metadata to help learn about the data at hand. An example of this could be looking at the raw data or hierarchically clustering samples and variables based on their similarity or differences.

I have been having some issues generating spatial unions and intersections using the rgeos package. The package is extremely powerful, as it serves as an R interface to the powerful GEOS engine. However, when working with shapefiles or polygons, quite often you will come across a whole range of errors, typically around topology exceptions. These occur

ggmap is a new tool which enables such visualization by combining the spatial information of static maps from Google Maps, OpenStreetMap, Stamen Maps or CloudMade Maps with the layered grammar of graphics implementation of ggplot2The library is developped by David Kahle and Hadley Wickham and in the latest R/Journal (Volume 5/1, June 2013),...

For database marketing or direct marketing people, they are always concerned about two questions before they send out mails or make calls to their customers:- How can they segment the customers in the database to find out who are more likely to response to their mails or buy their products? Which type of customers they

I frequently use lattice and ggplot2 to create trellis/faceted graphics. But, I gave up using these packages in a recent application, where I had initially constructed a complex graphic using the base R plotting functions. When I later decided that I wanted a faceted version, there was a dilema: re-create the complex graphic using lattice

Last post on modelling survival data from Veterinary Epidemiologic Research: parametric analyses. The Cox proportional hazards model described in the last post make no assumption about the shape of the baseline hazard, which is an advantage if you have no idea about what that shape might be. With a parametric survival model, the survival time

(This article was first published on Econometrics Beat: Dave Giles' Blog, and kindly contributed to R-bloggers) My post yesterday, on Allocation Models, drew a comment to the effect that in such models the dependent variables take values that must to be non-negative fractions. Well, as I responded, that’s true sometimes (e.g., in the case of market shares); but not in...

Revolution Analytics has a new office in London to serve our customers in Europe. This press release introduces the team members who are based there: Neil Miller, Managing Director, International: Neil Miller is responsible for Revolution Analytics' business and growth outside the Americas and is based in the U.K. Neil Miller joined the company after 14 years at Accenture...