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Programming Tips

Strengthen your programming skills with tips and techniques from the experts

Programming Tips

Rick WicklinAugust 26, 2020 0

Rewinding random number streams: An application

In the paper "Tips and Techniques for Using the Random-Number Generators in SAS" (Sarle and Wicklin, 2018), I discussed an example that uses the new STREAMREWIND subroutine in Base SAS 9.4M5. As its name implies, the STREAMREWIND subroutine rewinds a random number stream, essentially resetting the stream to the beginning.

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Learn SAS | Programming Tips

Rick WicklinAugust 24, 2020 0

How does PROC FCMP store functions?

I got a lot of feedback about my recent article about how to find roots of nonlinear functions by using the SOLVE function in PROC FCMP. A colleague asked how the FCMP procedure stores the functions. Specifically, why the OUTLIB= option on the PROC FCMP statement use a three-level syntax:

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Data Visualization | Programming Tips

Cindy WangAugust 20, 2020 0

Discover Visual Analytics Report Paths with REST APIs

SAS Viya is an open analytics platform accessible from interfaces or various coding languages. REST API is one of the widely used interfaces. Multiple resources exist on how to access SAS Visual Analytics reports using SAS Viya REST API. For example Programmatically listing data sources in SAS Visual Analytics by

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Programming Tips

Rick WicklinAugust 19, 2020 0

Find the root of a function by using the SAS DATA step

Finding the root (or zero) of a nonlinear function is an important computational task. In the case of a one-variable function, you can use the SOLVE function in PROC FCMP to find roots of nonlinear functions in the DATA step. This article shows how to use the SOLVE function to

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Advanced Analytics | Learn SAS | Programming Tips

Rick WicklinAugust 17, 2020 0

Estimate a power curve in parallel in SAS Viya

I recently showed how to use simulation to estimate the power of a statistical hypothesis test. The example (a two-sample t test for the difference of means) is a simple SAS/IML module that is very fast. Fast is good because often you want to perform a sequence of simulations over

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Data Management | Learn SAS | Programming Tips

Leonid BatkhanAugust 12, 2020 0

Expanding lengths of all character variables in SAS data sets

SAS' Leonid Batkhan reveals how to change lengths for all character variables in a data set and all data sets in a data library to facilitate data migration to Unicode encoding environment.

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Learn SAS | Programming Tips

Rick WicklinAugust 12, 2020 0

Use simulation to estimate the power of a statistical test

A previous article about standardizing data in groups shows how to simulate data from two groups. One sample (with n1=20 observations) is simulated from an N(15, 5) distribution whereas a second (with n2=30 observations) is simulated from an N(16, 5) distribution. The sample means of the two groups are close

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Learn SAS | Programming Tips

Rebecca Ottesen

Rebecca OttesenAugust 10, 2020 0

Learning to think like SAS

The most fundamental concept that students learning introductory SAS programming must master is how SAS handles data. This might seem like an obvious statement, but it is often overlooked by students in their rush to produce code that works. I often tell my class to step back for a moment

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Programming Tips

Rick WicklinAugust 10, 2020 0

4 ways to standardize data in SAS

A common operation in statistical data analysis is to center and scale a numerical variable. This operation is conceptually easy: you subtract the mean of the variable and divide by the variable's standard deviation. Recently, I wanted to perform a slight variation of the usual standardization: Perform a different standardization

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Learn SAS | Programming Tips

Rick WicklinAugust 5, 2020 0

Submatrices of matrices

Have you ever seen the "brain teaser" for children that shows a 4 x 4 grid and asks "how many squares of any size are in this grid?" To solve this problem, the reader must recognize that there are sixteen 1 x 1 squares, nine 2 x 2 squares, four 3 x 3 squares, and one 4 x 4 square.

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Learn SAS | Programming Tips

Rick WicklinAugust 3, 2020 0

Run tasks in parallel in SAS Viya

The iml action was introduced in Viya 3.5. As shown in a previous article, the iml action supports ways to implement the map-reduce paradigm, which is a way to distribute a computation by using multiple threads. The map-reduce paradigm is ideal for “embarrassingly parallel” computations, which are composed of many

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Programming Tips

Bari LawhornJuly 30, 2020 0

How to translate your cURL command into SAS code

You want to use an API to retrieve data and process it with SAS. How do you do it? PROC HTTP offers the features of the cURL command within your SAS code.

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Programming Tips

Rick WicklinJuly 29, 2020 0

Simulate regression models that incorporate CLASS parameterizations

When you write a program that simulates data from a statistical model, you should always check that the simulation code is correct. One way to do this is to generate a large simulated sample, estimate the parameters in the simulated data, and make sure that the estimates are close to

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Learn SAS | Programming Tips

Rick WicklinJuly 27, 2020 0

8 ways to use the Kronecker product

The Kronecker product (also called the direct product) is a binary operation that combines two matrices to form a new matrix. The Kronecker product appears in textbooks about the design of experiments and multivariate statistics. The Kronecker product seems intimidating at first, but often one of the matrices in the

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Data Management | Learn SAS | Programming Tips

Leonid BatkhanJuly 23, 2020 0

Splitting a data set into smaller data sets

SAS' Leonid Batkhan shows you how to split a large data set into many by a subsetting by a number of observations to produce smaller, better manageable data sets.

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Advanced Analytics | Machine Learning | Programming Tips

Rick WicklinJuly 23, 2020 0

Fit a multivariate Gaussian mixture model by using the expectation-maximization (EM) algorithm

Last month a SAS programmer asked how to fit a multivariate Gaussian mixture model in SAS. For univariate data, you can use the FMM Procedure, which fits a large variety of finite mixture models. If your company is using SAS Viya, you can use the MBC or GMM procedures, which

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Programming Tips

Steven SoberJuly 21, 2020 0

How to create a path-based CASLIB to SASWORK for speedier analysis with SAS® Viya®

Is there programmatic way to reduce memory requirements of a CAS table in SAS® Viya®? Yes! SAS' Steven Sober shows you how.

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Learn SAS | Programming Tips

Rick WicklinJuly 20, 2020 0

Compute within-group multivariate statistics and store them in a list

I recently showed how to compute within-group multivariate statistics by using the SAS/IML language. However, a principal of good software design is to encapsulate functionality and write self-contained functions that compute and return the results. What is the best way to return multiple statistics from a SAS/IML module? A convenient

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Advanced Analytics | Programming Tips

Rick WicklinJuly 15, 2020 0

How to evaluate the multivariate normal log likelihood

The multivariate normal distribution is used frequently in multivariate statistics and machine learning. In many applications, you need to evaluate the log-likelihood function in order to compare how well different models fit the data. The log-likelihood for a vector x is the natural logarithm of the multivariate normal (MVN) density

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Programming Tips

James Gearheart

James GearheartJuly 14, 2020 0

Adjusting outliers with the 1.5 IQR rule

In my new book, End-to-End Data Science with SAS: A Hands-On Programming Guide, I use the 1.5 IQR rule to adjust multiple variables. This program utilizes a macro that loops through a list of variables to make the necessary adjustments and creates an output data set. One of the most

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Learn SAS | Programming Tips

Rick WicklinJuly 13, 2020 0

A parallel implementation of Monte Carlo simulation in SAS Viya

A previous article introduces the MAPREDUCE function in the iml action. (The iml action was introduced in Viya 3.5.) The MAPREDUCE function implements the map-reduce paradigm, which is a two-step process for distributing a computation to multiple threads. The example in the previous article adds a set of numbers by

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Data Visualization | Programming Tips

Robert AllisonJuly 10, 2020 0

Pandemic code samples, for SAS graphics

During the 2020 Coronavirus pandemic, you've probably formed a great appreciation for good, informative graphics. Good graphics can help you get a handle on thousands of individual data values, see the geographical distribution, or look for trends. In February, I wrote a blog post about creating a coronavirus dashboard with

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Programming Tips

Chris Hemedinger

Chris HemedingerJuly 9, 2020 0

Using SAS with Microsoft 365 (OneDrive, Teams, and SharePoint)

Learn how to use SAS code (PROC HTTP) to read and write files from your Microsoft OneDrive, Microsoft Teams or SharePoint Online. You'll learn how to create a Microsoft Office 365 app, connect to it with SAS, and automate the integration with your office productivity environment.

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Learn SAS | Programming Tips

Rick WicklinJuly 8, 2020 0

A general method for parallel computation in SAS Viya

The iml action in SAS Viya (introduced in Viya 3.5) provides a set of general programming tools that you can use to implement a custom parallel algorithm. This makes the iml action different than other Viya actions, which use distributed computations to solve specific problems in statistics, machine learning, and

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Programming Tips

Peter Styliadis

Peter StyliadisJuly 7, 2020 0

Getting Started with Python Integration to SAS® Viya® - Part 3 - Loading a CAS Action Set

Are you looking for a specific CAS action to use in your project? Maybe you need to create a linear or logistic regression and can't seem to find the CAS action? In this post in the Getting Started with Python Integration to SAS® Viya® series, we are going to look

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Analytics | Learn SAS | Programming Tips | Students & Educators

Jihye YooJuly 7, 2020 0

새로워진 SAS 커뮤니티를 소개합니다

오랜 시간동안 많은 사랑을 받아온 SAS 사용자 커뮤니티가 리뉴얼되었습니다. 한국에서 SAS 커뮤니티의 역사는 벌써 30년이 되었습니다. 1990년 SAS코리아 설립 이후 SAS User Group International-Korea(SUGI-K)라는 이름으로 활동한 SAS 사용자 모임이 2007년 MYSAS로 명칭을 바꾸었습니다. 그리고, 2010년 홈페이지를 개편하고 10년 만인 2020년, 사용자 모임의 활성화를 위해 새로운 SAS 커뮤니티 사이트로 여러분을 다시

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Programming Tips

Rick WicklinJuly 6, 2020 0

Pool testing: The math behind combining medical tests

Testing people for coronavirus is a public health measure that reduces the spread of coronavirus. Dr. Anthony Fauci, a US infectious disease expert, recently mentioned the concept of "pool testing." The verb "to pool" means "to combine from different sources." In a USA Today article, Dr. Deborah Birx, the coordinator

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Programming Tips

Rick WicklinJune 29, 2020 0

What is a pooled variance?

The first time I saw a formula for the pooled variance, I was quite confused. It looked like Frankenstein's monster, assembled from bits and pieces of other quantities and brought to life by a madman. However, the pooled variance does not have to be a confusing monstrosity. The verb "to

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Programming Tips

Ron CodyJune 24, 2020 0

Multi-way lookup tables

A lookup table is a programming technique where one or more values can be used to retrieve another value. For example, many years ago, I had benzene exposure estimates for 10 years (1940 to 1949) for each of five locations in a factory. Given a year and a job location,

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Analytics | Programming Tips

Rick WicklinJune 24, 2020 0

The Kolmogorov D distribution and exact critical values

If you have ever run a Kolmogorov-Smirnov test for normality, you have encountered the Kolmogorov D statistic. The Kolmogorov D statistic is used to assess whether a random sample was drawn from a specified distribution. Although it is frequently used to test for normality, the statistic is "distribution free" in

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