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Programming Tips

Strengthen your programming skills with tips and techniques from the experts

Learn SAS | Programming Tips

Rick WicklinFebruary 7, 2022 0

Billiards on an elliptical table

I recently showed how to find the intersection between a line and a circle. While working on the problem, I was reminded of a fun mathematical game. Suppose you make a billiard table in the shape of a circle or an ellipse. What is the path for a ball at

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Analytics | Programming Tips

Rick WicklinFebruary 2, 2022 0

Implement a line search algorithm in SAS

Recently, I needed to implement a line search algorithm in SAS. The line search is illustrated by the figure at the right. You start with a point, p, in d-dimensional space and a direction vector, v. (In the figure, d=2, but in general d > 1.) The goal is to

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Analytics | Data Visualization | Programming Tips

Nicole BallFebruary 1, 2022 0

You can’t teach an old dog new tricks… or can you?

When we moved out to the country with our two dogs, our oldest dog Todd suddenly decided he liked to howl…. And he would do so every time we left the house. Maybe it was the country air? Maybe it was a time-lapse gene? Maybe he just wanted to learn

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Analytics | Programming Tips

Rick WicklinJanuary 31, 2022 0

The ERF and ERFC functions for statisticians

Recently, a SAS programmer commented about one of my blog posts. He said that he had found an alternative answer on another website. Whereas my answer was formulated in terms of the normal cumulative distribution function (CDF), the other answer used the ERF function. This article shows the relationship between

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Analytics | Artificial Intelligence | Programming Tips | Students & Educators

Yinliang WuJanuary 28, 2022 0

Solve "A Puzzle for Pirates" with SAS

This article introduces how to solve the pirate game with a recursive solving algorithm in SAS, and how to analyze and visualize the law behind the complex logic of the pirate game. If you join in a pirate game next time, you can know your destiny ahead of time to reap the benefits and avoid getting killed.

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Programming Tips

Ron CodyJanuary 27, 2022 0

How to use the SAS Auto Call facility

Many SAS programmers use macros. I have seen students in my SAS classes use several methods to activate their macros. One way is to load the macro in the Display manager or editor in SAS OnDemand for Academics and submit it. Another technique is to use the statement %Include macro-name.

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Learn SAS | Programming Tips

Rick WicklinJanuary 26, 2022 0

4 ways to find the k smallest and largest data values in SAS

Sometimes it is useful to know the extreme values in data. You might need to know the Top 5 or the Top 10 smallest data values. Or, the Top 5 or Top 10 largest data values. There are many ways to do this in SAS, but this article shows examples

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Analytics | Learn SAS | Programming Tips

Rick WicklinJanuary 24, 2022 0

Estimate percentiles in SAS Viya

How can you estimate percentiles in SAS Viya? This article shows how to call the percentile action from PROC CAS to estimate percentiles of variables in a CAS data table. Percentiles and quantiles are essentially the same (the pth quantile is the 100*pth percentile for p in [0, 1]), so

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Programming Tips

Rick WicklinJanuary 20, 2022 0

How often do different statistical tests agree? A simulation study

Here's a fun problem to think about: Suppose that you have two different valid ways to test a statistical hypothesis. For a given sample, will both tests reject or fail to reject the hypothesis? Or might one test reject it whereas the other does not? The answer is that two

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Programming Tips

Image of SAS Studio GIT page

SAS JediJanuary 18, 2022 0

Jedi SAS Tricks: GIT my macros

I use macros extensively in my SAS programs, and over the years have accumulated a few that I find quite useful. The integration of GIT and SAS Studio has made it easy to build a re-usable macro library, so I've put some of the more polished macros I've written in

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Learn SAS | Programming Tips

Rick WicklinJanuary 18, 2022 0

Simulate events when some probabilities are zero

Several probability distributions model the outcomes of various trials when the probabilities of certain events are given. For some distributions, the definitions make sense even when a probability is 0. For other distributions, the definitions do not make sense unless all probabilities are strictly positive. This article examines how zero

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Programming Tips

Leonid BatkhanJanuary 13, 2022 0

Calculating the overlap of date/time intervals

Leonid Batkhan describes and discusses pros and cons of 3 different algorithms and SAS code implementations to calculate length of overlap of date/time intervals and integer intervals in general.

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Programming Tips

Rick WicklinJanuary 12, 2022 0

How to assign a name to a color

Some colors have names, such as "Red," "Magenta," and "Dark Olive Green." But the most common way to specify a color is to use a hexadecimal value such as CX556B2F. It is not obvious that "Dark Olive Green" and CX556B2F represent the same color, but they do! I like to

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Programming Tips

Ron CodyJanuary 11, 2022 0

Two macros for detecting data errors

Last year, I wrote a blog demonstrating how to use the %Auto_Outliers macro to automatically identify possible data errors. This blog demonstrates a different approach—one that is useful for variables for which you can identify reasonable ranges of values for each variable. For example, you would not expect resting heart

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Analytics | Learn SAS | Programming Tips

Rick WicklinJanuary 10, 2022 0

12 blog posts from 2021 that deserve a second look

On this blog, I write about a diverse set of topics that are relevant to statistical programming and data visualization. In a previous article, I presented some of the most popular blog posts from 2021. The most popular articles often deal with elementary or familiar topics that are useful to

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Programming Tips

Peter Styliadis

Peter StyliadisJanuary 7, 2022 0

Getting Started with Python Integration to SAS® Viya® - Part 6 - Descriptive Statistics

Welcome to the sixth installment in my series Getting Started with Python Integration to SAS Viya. In previous posts, I discussed how to connect to the CAS server, how to execute CAS actions, and how to work with the results. Now it's time to generate simple descriptive statistics of a CAS table. Let's begin

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Programming Tips

Rick WicklinJanuary 5, 2022 0

A block-Cholesky method to simulate multivariate normal data

You can use the Cholesky decomposition of a covariance matrix to simulate data from a correlated multivariate normal distribution. This method is encapsulated in the RANDNORMAL function in SAS/IML software, but you can also perform the computations manually by calling the ROOT function to get the Cholesky root and then

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Analytics | Data Visualization | Programming Tips

Rick WicklinJanuary 3, 2022 0

Top 10 posts from The DO Loop in 2021

Last year, I wrote almost 100 posts for The DO Loop blog. My most popular articles were about data visualization, statistics and data analysis, and simulation and bootstrapping. If you missed any of these gems when they were first published, here are some of the most popular articles from 2021:

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Programming Tips

Yinliang WuDecember 23, 2021 0

SAS financial functions review and mortgage payment analysis

Let's take a look at the design and implementation of SAS functions in financial calculations. We'll do this through examples calculating and analyzing the monthly payment, interest, and principal for CPM/CAM mortgages.

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Programming Tips

Ron CodyDecember 16, 2021 0

Summarizing data

Because it is near the end of the year, I thought a blog about "Summarizing" data might be in order. For these examples, I am going to use a simulated data set called Drug_Study, containing some categorical and numerical variables. For those interested readers, the SAS code that I used

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Programming Tips

Marcia SurrattDecember 10, 2021 0

How to view CAS tables in SAS® Studio

CAS libraries enable you to access your CAS data. By defining the librefs for those caslibs in SAS Studio, you can have more interactive access to the CAS data.

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Cloud | Programming Tips | SAS Administrators

Anthony KanDecember 6, 2021 0

A Novice Perspective on SAS Viya Deployment

This post is written in the hopes of easing the SAS Viya deployment process for novices like me. Firstly, deploying SAS Viya, like most enterprise software packages, isn't a skill we're innately born with. We're going to need a little help, some good documentation, and time to absorb the intricoes

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Analytics | Programming Tips

Rick WicklinDecember 6, 2021 0

The expected number of points on a convex hull

While discussing how to compute convex hulls in SAS with a colleague, we wondered how the size of the convex hull compares to the size of the sample. For most distributions of points, I claimed that the size of the convex hull is much less than the size of the

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Programming Tips

Lora D. DelwicheDecember 3, 2021 0

Using variable names with special characters

When we wrote the sixth edition of The Little SAS Book: A Primer, one of our goals was to write it for all SAS programmers regardless of which interface they use for coding: SAS Studio, SAS Enterprise Guide, the SAS windowing environment, or batch. This is harder than it sounds.

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Data Visualization | Programming Tips

Robert AllisonNovember 29, 2021 0

Enhancing a scatter plot

A scatter plot is my go-to graph! It's what I often start with to get a feel for the data ... and I often end up using just a scatter plot. But some scatter plots are better than others ... In this blog post, I create a scatter plot of

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Learn SAS | Programming Tips

Rick WicklinNovember 29, 2021 0

Caslibs and librefs in SAS Viya

When SAS 9 programmers transition to SAS Viya, there are inevitably questions about how new concepts in Cloud Analytic Services (CAS) relate to similar concepts in SAS. This article discusses the question, "What is the difference between a libref and a caslib?" Both are used to access data, but they

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Data Visualization | Programming Tips

Rick WicklinNovember 17, 2021 0

The order of vertices on a convex polygon

In a previous article, I showed how to use theCVEXHULL function in SAS/IML to compute the convex hull of a finite set of planar points. The convex hull is a convex polygon, which is defined by its vertices. To visualize the polygon, you need to know the vertices in sequential

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Programming Tips

Ron CodyNovember 16, 2021 0

Creating Simulated Data Sets (Part Two)

This blog is a continuation of a previous blog that discussed creating simulated data sets. If you have not seen it, you might want to review it, especially if you are not familiar with the RAND function. The program that I'm going to show you simulates a drug study with

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Data Visualization | Learn SAS | Programming Tips

Rick WicklinNovember 15, 2021 0

Two-dimensional convex hulls in SAS

Given a cloud of points in the plane, it can be useful to identify the convex hull of the points. The convex hull is the smallest convex set that contains the observations. For a finite set of points, it is a convex polygon that has some of the points as

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Data Visualization | Programming Tips

Robert AllisonNovember 11, 2021 0

Where do Canadians live?

Canada is a geographically large country, but I've heard that much of the population lives in the small southernmost sections (near the US border). I decided to use my mapping skills, and put that to the test. Follow along, and we'll see what that looks like on a map ...

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