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Analytics | Data Visualization | Learn SAS | Programming Tips

Rick WicklinJanuary 13, 2025 1

12 blog posts from 2024 that deserve a second look

In a previous article, I presented some of the most popular blog posts from The DO Loop in 2024. In general, popular articles deal with elementary topics that have broad appeal. However, I also write technical articles about advanced topics, which typically do not make it onto a Top 10

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Analytics | Data Visualization | Learn SAS | Programming Tips

Rick WicklinJanuary 6, 2025 1

Top 10 posts from The DO Loop in 2024

In 2024, I wrote about 80 articles for The DO Loop blog. My most popular articles were about SAS programming, data visualization, and statistics. If you missed any of these articles, here is the "Reader's Choice Awards" for some of the most popular articles from 2024! SAS Programming The following

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Analytics | Programming Tips

Rick WicklinDecember 18, 2024 1

Generate correlation matrices with specified eigenvalues

A previous article discusses how to generate a random covariance matrix with a specified set of (positive) eigenvalues. A SAS programmer asked whether it is possible to produce a correlation matrix that has a specified set of eigenvalues. After discussing the problem with a friend, I am happy to report

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Data Visualization | Learn SAS | Programming Tips

Rick WicklinDecember 16, 2024 1

A normal Christmas tree

O Christmas tree, O Christmas tree, How lovely are your branches! SAS programmers have a long history of creating yuletide-themed graphics. Christmas trees are a popular image because of their simplicity. I admit that I have indulged more than once in this holiday tradition: An old-school ASCII art image A

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Advanced Analytics | Programming Tips

Rick WicklinDecember 9, 2024 0

Latin hypercube sampling in SAS

While researching the topic of Latin hypercube sampling (LHS), I read an article by Emily Gao (2019) that shows how to use PROC IML in SAS to perform the algorithm. It is possible to simplify Gao's implementation of Latin hypercube sampling in SAS while also making the computation more efficient.

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Analytics | Programming Tips

Rick WicklinDecember 2, 2024 3

A historical method of generating random normal variates

Decades ago, it was a challenge to generate (pseudo-) random numbers that had good statistical properties. The proliferation of desktop computers in the 1980s and '90s led to many advances in computational mathematics, including better ways to generate pseudorandom variates from a wide range of probability distributions. (For brevity, I

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Analytics | Learn SAS | Programming Tips

Rick WicklinNovember 20, 2024 1

Order two-dimensional vectors by using angles

Order matters. The order of variables in tables and rows of a correlation matrix can make a big difference in how easy it is to observed correlations between variables or groups of variables. There are many ways to order the variables, but this article shows how to display the variables

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Learn SAS | Programming Tips

Rick WicklinNovember 13, 2024 4

A vector-to-string function for SAS IML

A previous article discusses the MakeString function, which you can use to convert an IML character vector into a string. This can be very useful. When I originally wrote the MakeString function, I was disappointed that I could not vectorize the computation. Recently, I learned about the COMBL function in

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Learn SAS | Programming Tips

Rick WicklinNovember 4, 2024 0

Levy flight and vectorizing a simulation in SAS

A previous article shows a simulation of two different models of a foraging animal. The first model is a random walk, which assumes that the animal chooses a random direction, then takes a step that is distributed according to a Gaussian random variable. In the second model, the animal again

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Data Visualization | Learn SAS | Programming Tips

Rick WicklinOctober 28, 2024 3

Automate the creation of a range attribute map in SAS

In SAS, range attribute maps enable you to specify the range of values that determine the colors used for graphical elements. There are various examples that use the GTL to define a range attribute map, but fewer examples that show how to use a range attribute map with PROC SGPLOT.

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