London, 1772. I have been asked by my superiors to give a brief demonstration of the surprising effectiveness of even the simplest techniques of the new-fangled Social Networke Analysis in the pursuit of those who would seek to undermine the liberty enjoyed by His Majesty's subjects. This is in connection with ... [Read more...]

Month after month, one of the most popular posts on the Paleocave blog is the How to Read a Cladogram post I did some time ago. I always intended to follow it up with more cladistic fun. So, hold onto your butts, we’re going to let the dinosaurs loose. ... [Read more...]

Better Neighborhoods with R: Exploring and Analyzing SeeClickFix Data (part 1) The ‎ National Day of Civic Hacking took place …Continue reading » [Read more...]

When managing big data with R, many people like to use sqldf() package due to its friendly interface or choose data.table() package for its lightening speed. However, very few would pay special attentions to small details that might significantly boost the efficiency of these packages by adding index to ... [Read more...]

I have a few posts coming up on Apache Mahout so I thought it might be useful to share some notes. I came at it as primarily an R coder with some very rusty Java and C++ somewhere in the back of my head so that will be my point ... [Read more...]

Here, or there, I read many techniques to import a large dataset in R. The option read.table or read.csv doesn't work anyway because, as discusshere, R load in memory. And sometimes, when we try to load a big dataset, we got this message : Warning messages:  1: Reached total allocation ... [Read more...]

Following up on my previous post regarding attrition rates at Comrades Marathon 2013, here are the statistics I have gathered for medal allocations. There is some interesting history behind the Comrades Marathon medals. For reference, the medals are allocated as follows: Gold medals to the first ten finishers in the men’... [Read more...]

Introduction Recently, I began a series on exploratory data analysis; so far, I have written about computing descriptive statistics and creating box plots in R for a univariate data set with missing values.  Today, I will continue this series by analyzing the same data set with kernel density estimation, a ... [Read more...]

The measures of position such as quartiles, deciles, and percentiles are available in quantile function. This function has a usage,where:x - the data pointsprob - the location to measurena.rm - if FALSE, NA (Not Available) data points are not ignoredna... [Read more...]

In my post on 06/05/2013 (http://statcompute.wordpress.com/2013/06/05/estimating-composite-models-for-count-outcomes-with-fmm-procedure), I’ve shown how to estimate finite mixture models, e.g. zero-inflated Poisson and 2-class finite mixture Poisson models, with FMM and NLMIXED procedure in SAS. Today, I am going to demonstrate how to achieve the same results with flexmix package ... [Read more...]

Sometimes I just want to quickly make a simple D3 JavaScript directed network graph with data in R. Because D3 network graphs can be manipulated in the browser–i.e. nodes can be moved around and highlighted–they're really nice for data exploration. They're also really nice in HTML presentations. ... [Read more...]

Mean in R is computed using the function mean. Consider the scores of 20 MSU-IIT students in Stat 101 exam with a hundred items: 70, 78, 66, 65, 50, 53, 48, 88, 95, 80, 85, 84, 81, 63, 68, 73, 75, 84, 49, and 77. Compute and interpret the mean and medi... [Read more...]

# There are several domain name servers that allow # for bulk searching of domain names.# http://www.godaddy.com/bulk-domain-search.aspx# http://www.namestation.com/bulk-domain-search# However, they do not provide any wildcard support # and instead exp... [Read more...]

Matrix manipulation in R are very useful in Linear Algebra. Below are lists of common yet important functions in dealing operations with matrices:Transpose - tMultiplication - %*%Determinant - detInverse - solve, or ginv of MASS libraryEigenvalues and ... [Read more...]

MongoDB is a document-based noSQL database. Different from the relational database storing data in tables with rigid schemas, MongoDB stores data in documents with dynamic schemas. In the demonstration below, I am going to show how to extract data from a MongoDB with R. Before starting the R session, we ... [Read more...]

I’ve seen it happens quite often. The sig test. Somebody simply needs to know the p-value and that one number will provide all of the information about the study that they need to know. The dataset is presented and the client/boss/colleague/etc invariably asks the question “is ... [Read more...]

Corey Yanofsky writes: In your work, you’ve robustificated logistic regression by having the logit function saturate at, e.g., 0.01 and 0.99, instead of 0 and 1. Do you have any thoughts on a sensible setting for the saturation values? My intuition suggests that it has something to do with proportion of outliers ... [Read more...]

I grew up in Australia, where I learned to speak English. Or so I thought: when I moved overseas to the UK, and especially when I moved to the States, I soon learned these are distinct cultures separated by a common language. Words which I previously had no context for ... [Read more...]

My book about Rcpp (and its R and C++ integration) is now available from Springer. Amazon still lists it as not-yet-released; I expect this to change in the next few days. [Read more...]

Two years ago the first version of rasterVis was submitted to R-Forge and some weeks after the first stable version was …Continuar leyendo » [Read more...]