Tag Archives: R software

PMean: How to run your first Bayesian analysis using jags software in R

Someone wanted to know how to run a Bayesian data analysis for a two group longitudinal study. There are several ways you can do this, but I had to confess I did not have an immediate answer. So I took some time to figure out how to do this using jags software inside of R. I’ve done a fair amount of stuff in jags, but not anything close to a longitudinal design. The general principle is to start with something easy and work your way slowly up to the final analysis. Continue reading

PMean: Measuring pixels in an R graph

I have an R cheat sheet, How Big Is Your Graph, that explains how to measure the size of various features of your graph in R. This blog post illustrates unit conversions. If you want to measure the length of a diagonal line segment in an R graph, you need to calculate the size of the plotting region in pixels, compare that to the range of the plotting region in the x and y directions, and then apply the Pythagorean Theorem. Continue reading

Recommended: Where Do You Run Your R Scripts?

I’m an experienced R programmer trying to learn a little about SQL. One of my good friends who lives totally in the database world (I call her the Teradata Queen), shared a link to a blog post at SQLServerCentral about using R. Microsoft is including R in its SQL Server distribution, so this is an opportunity for a lot of interesting work combining the data manipulation power of SQL Server with the data analysis power of R. Anyway, the blog post explains some of the cost and performance issues associated with R scripts running on a SQL Server CPU. Continue reading

PMean: Turning off large blocks of an R Markdown document

When you’re running a large and complicated program using R Markdown, you can use the CACHE option to save a lot of time. CACHE will notice if a program chunk has stayed the same and avoid running it again. I tend to avoid using the CACHE option, though, because sometimes it fails to execute something that you want executed, even though it looks on the surface like nothing has changed. So I created some simple program chunks that allow me to explicitly turn off parts of the R Markdown program that I don’t need to evaluate at the time. Think of it as a manual cache.

It’s a very simple thing, but one which confounded me for a while, so I am writing about it here. That way I won’t forget six months down the road. Continue reading