Inspired by this blog post from theBioBucket, I created a script to parse all pdf files in a directory. Due to its reliance on the Terminal, it’s Mac specific, but modifications for other systems shouldn’t be too hard (as a start for Windows, see BioBucket’s script). First, you have to install the command line tool
Monthly Archives: October 2012
Generating Tests of Particular Properties
# This post will demonstrate how to generate total test score distributions from a set of 50 items.# It will build on a previous post (http://www.econometricsbysimulation.com/2012/09/simulating-3-parameter-irt-data.html) that demonstrated how to easily...
Log odds ratios and an indicator matrix from categorical data
A long title, but there are a couple of handy things in this Gist. The first, and more obscure, is the conversion of a data.frame of categorical variables into a matrix of dummy/binary/indicator variables, one for each category of each original variab...
Graphing Non-Proportional Hazards in R
(This article was first published on Christopher Gandrud (간드루드 크리스토파), and kindly contributed to R-bloggers) To leave a comment for the author, please follow the link and comment on his blog: Christopher Gandrud (간드루드 크리스토파). R-bloggers.com offers daily e-mail updates about R news and tutorials on topics such as: visualization (ggplot2, Boxplots, maps, animation), programming (RStudio, Sweave, LaTeX, SQL,...
Tips on accessing data from various sources with R
Jeffrey Breen (the man behind the Twitter airline sentiment analysis example) recently posted a collection of slides with some great tips for accessing data from R. "Tapping the Data Deluge" includes information on: Using the XLConnect package to read data from Excel spreadsheets Using the foreign package to read SPSS, SAS, Stata and dBase data files Using SQL queries...
Have I chosen the right power company?
Do you always wonder if I have chosen the right power company and have not been over charged? Your questions may be answered here (if you reside in Wellington, New Zealand). Power costs per day and per month_Oct_2012 shows which company … Continue reading →
Perculiar behaviour of the sum function
The sum function in R is a special one in contrast to other summary statistics functions such as mean and median. The first distinguish is that it is a Primitive function where the others are not (Although you can call mean using .Internal). This ...
Transforming a color scale
In developing plots, I often use color (or “colour” in ggplot2 parlance) to reflect values of a third, non-X/Y, variable. Depending on the distribution of this Z variable, however, the effective color range can be narrow, making it difficul...
A Quick Note On Large 2D Data
Two months ago I was told one of my old blog posts was borrowed to this post: Finding patterns in big data with SAS/GRAPH. I wrote my blog post four years ago just for fun. The over-plotting issue is pretty boring to me now, but what caught my attentio...
Emerging as Low Vol
Extending the series begun with When Russell 2000 is Low Vol, I thought I should take a look at Emerging Market stocks during periods of low relative volatility to the S&P 500. So you can replicate even without access to expensive data, let
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
