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The initial version of the timeline package has been released to CRAN. This package provides creates timeline plots using ggplot2 in a style similar to Preceden. I would considered this beta quality as there are more features I would like to add but has enough functionality to possibly be useful ... [Read more...]

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Frequently I need to recode a date column to quarters. For example, at Excelsior College we have continuous enrollment so we report new enrollments per quarter. To complicate things a bit, our fiscal year starts in July so that July, August, and September represent the first quarter, January, February, and ... [Read more...]

When I went to school we were always taught the “i before e, except after c” rule for spelling. But how accurate is this rule? Kevin Marks tweeted today the following: »@uberfacts: There are 923 words in the English language that break the “I before E” rule. Only 44 words actually follow ... [Read more...]

Version 1.0 of multilevelPSA has been released to CRAN. The multilevelPSA package provides functions to estimate and visualize propensity score models with multilevel, or clustered, data. The graphics are an extension of PSAgraphics package by Helmreich and Pruzek. The example below will investigate the differences between private and public school internationally ... [Read more...]

There are many situations in R where you have a list of vectors that you need to convert to a data.frame. This question has been addressed over at StackOverflow and it turns out there are many different approaches to completing this task. Since I encou... [Read more...]

I posted a question over on StackOverflow on an efficient way of comparing two data frames with the same column structure, but with different rows. What I would like to end up with is an n x m logical matrix where n and m are the number of rows in ... [Read more...]

Version 1.0 of sqlutils has been released to CRAN. The sqlutils package is designed to manage a library of SQL files. This package grew out of the needs of an Office of Institutional Research where the vast majority of analysis is conducted on data from our Student Information System (SIS) which ... [Read more...]

I recently taught a very basic introduction to SQL workshop and needed a way to have participants interact with SQL statements. Obviously there are lots of tools to interface with a database, but since we are all R users I thought it would be nice to be able interact without ... [Read more...]

One issue I continuously encounter when starting to work with a new dataset is that of the codebook. In general, I prefer to load a codebook into R like any other data source, specifically as a data frame. And ideally, one data frame to provides the variable names with descriptions ... [Read more...]

The xtable package is tremendously useful for generating LaTeX tables from data frames. It is also pretty easy to customize the output to handle some special cases of LaTeX formatting. The xtable.decimal function will create a LaTeX table where numeric columns will be vertically aligned on the decimal point. ... [Read more...]

Introduction Markdown has been growing in popularity for writing documents on the web. With the introduction of R Markdown (see also Jeromy Anglim’s post on getting started with R Markdown) and knitr, R Markdown has simplified the publishing of R analysis on the web. I recently converted my website ... [Read more...]

My wife went out to her book group tonight and their book of the month was 50 Shades of Grey. Sadly, I could think of is that plotting 50 shades in R would be a neat exercise. require(ggplot2) grey50 [Read more...]

We all know that the odds of flipping an unbiased coin is 50% heads, 50% tails. But what happens if you do this a lot of times. Do you expect the same number of heads and tails? What if we took a cumulative sum where heads = +1 and tails = -1. What wou... [Read more...]

There are several graphics available for visualizing missing data including the VIM package. However, I wanted a plot specifically for looking at the nature of missingness across variables and a clustering variable of interest to support data preparati... [Read more...]

I was inspired by Kay Cichini  recent post on creating a a tcl/tk dialog box for users to enter variable values. I am going to have a use for this very soon so took some time to make it a bit more generic. What I wanted is a function ... [Read more...]

Following up on John Mount’s post on remembering symbol parameters in ggplot2, I decided to give it a try and included symbols, line types, and colors (based upon Earl Glynn’s wonderful color chart).  Code follows below. require(ggplot2) ... [Read more...]

For the longest time I resisted customizing R for my particular environment. My philosophy has been that each R script for each separate analysis I do should be self contained such that I can rerun the script from top to bottom on any machine and get the same results. This ... [Read more...]

If you are reading this vis-à-vis R-Bloggers, then you know how good R, LaTeX, and Sweave are for generating reports and/or conducting reproducible research. It has been particularly valuable for me in Institutional Research where there are many reports that I need to prepare on a regular basis (... [Read more...]