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Today the two-year-old TLS security certificate for cran.r-project.org expired, so suddenly in R you are getting errors running install.packages or update.packages. The error looks like this:__ update.packages()--- Please select a CRAN mirror for use in this session ---Error in download.file(url, destfile = f, ... [Read more...]

Today the two-year-old TLS security certificate for cran.r-project.org expired, so suddenly in R you are getting errors running install.packages or update.packages. The error looks like this: __ update.packages()--- Please select a CRAN mirror for use in this session ---Error in download.file(url, destfile = f, ... [Read more...]

This R command lists all the packages installed by the user (ignoring packages that come with R such as base and foreign) and the package versions. ip rownames(ip) ip print(ip, row.names=FALSE) Example output Package Version bitops 1.0-6 BradleyTerry2 1.0-6 brew 1.0-6 brglm 0.5-9 car 2.0-25 caret 6.0... [Read more...]

You already know that a SQL INSERT is faster with bulk loading than inserting a record at a time, but what about the effect of autocommit on performance? While this is probably not specific to ceODBC, using autocommit is astonishingly slow. Here is how slow. First, the Python code to ... [Read more...]

Because the Fibonacci sequence is simply defined by recursion, it makes for an elegant programming exercise. Here is one way to do it in SAS, and another way to do it in R. I've also included unit testing code to check that it works. Fibonacci sequence in SAS using a ... [Read more...]

Principal Components Analysis (PCA) is used as a dimensionality reduction method. Here we simply explain PCA step-by-step using data about Sochi Olympic Curlers. It is hard to visualize a high dimensional space. When I took linear algebra, the book and teachers spoke about it as if were easy to visualize ... [Read more...]

This simulation tests the type I error rates of the Shapiro-Wilk test of normality in R and SAS. First, we run a simulation in R. Notice the simulation is vectorized: there are no "for" loops that clutter the code and slow the simulation. # type I erroralpha [Read more...]