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Programming Tips

Strengthen your programming skills with tips and techniques from the experts

Programming Tips

Rick WicklinAugust 2, 2021 0

The art of rotations and reflections

Art evokes an emotional response in the viewer, but sometimes art also evokes a cerebral response. When I see patterns and symmetries in art, I think about a related mathematical object or process. Recently, a Twitter user tweeted about a painting called "Phantom’s Shadow, 2018" by the Nigerian-born artist, Odili

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Data Visualization | Programming Tips

Robert AllisonJuly 30, 2021 0

Have deaths in the US been increasing, or decreasing?

Some claim that deaths in the US have been increasing, and some claim they have been decreasing. Which do you think is correct? Let's take a look at the data ... The Data Here in the US, the Centers for Disease Control and Prevention is a good/official source of data

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Analytics | Programming Tips

Randy CollicaJuly 29, 2021 0

An analytic transform for cantankerous data

As an example, when using ordinary least squares regression (OLS), if your response or dependent attribute’s residuals are not normally distributed, your analysis is likely going to be affected and typically not in a good way. The farther away your input data is from normality, the impact on your model

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Data Visualization | Programming Tips

Robert AllisonJuly 27, 2021 0

How to make your data look worse (than it really is)

"With great power comes great responsibility." I'm not sure exactly where this quote comes from, but I think everyone should keep it in mind when creating graphs and maps! There are many design decisions that can influence how the end user perceives the data in a graph. For example: The

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Programming Tips

Ron CodyJuly 27, 2021 0

The Amazing COMPRESS Function

In the past, the COMPRESS function was useful. Since SAS version 9, it has become a blockbuster, and you might not have noticed. The major change was the addition of a new optional parameter called MODIFIERS. The traditional use of the COMPRESS function was to remove blanks or a list

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Programming Tips

Rick WicklinJuly 26, 2021 0

Compare the default definitions for sample quantiles in SAS, R, and Python

A SAS programmer recently asked why his SAS program and his colleague's R program display different estimates for the quantiles of a very small data set (less than 10 observations). I pointed the programmer to my article that compares the nine common definitions for sample quantiles. The article has a

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Programming Tips | SAS Administrators

Ben YarbroughJuly 23, 2021 0

How to use the SAS® 9 Content Assessment Tool

SAS' Ben Yarbrough reveals the four questions to answer and four steps to take as you transition to SAS Viya.

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Analytics | Data Visualization | Programming Tips

Rick WicklinJuly 19, 2021 0

Copulas and multivariate distributions with normal marginals

After my recent articles on simulating data by using copulas, many readers commented about the power of copulas. Yes, they are powerful, and the geometry of copulas is beautiful. However, it is important to be aware of the limitations of copulas. This article creates a bizarre example of bivariate data,

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Data Visualization | Programming Tips

Robert AllisonJuly 14, 2021 0

SAS can turn your world upside down!

Who's to say that 'north' should always be at the top of a map? Perhaps in certain situations, you might want 'south' (or some other direction) to be at the top. Perhaps you're one of our crazy Australian customers who looks at the world a little differently. Well, whatever the

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Analytics | Programming Tips

Rick WicklinJuly 14, 2021 0

Compare computational methods for least squares regression

In a previous article, I discussed various ways to solve a least-square linear regression model. I discussed the SWEEP operator (used by many SAS regression routines), the LU-based methods (SOLVE and INV in SAS/IML), and the QR decomposition (CALL QR in SAS/IML). Each method computes the estimates for the regression

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Programming Tips

Chris DeHartJuly 12, 2021 0

The SAS/ACCESS Developer's Corner: SUBCHAR-acteristics

Understanding the problem Working with character data of different encodings across different systems can occasionally result in failures to translate or transcode that data from its source format to a destination format. When using a SAS/ACCESS LIBNAME engine to query DBMS data, this scenario can end up causing errors when

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Data Visualization | Programming Tips

Robert AllisonJuly 8, 2021 0

Plagues and locusts ... or is that cicadas?

I hope you're all doing well, in this year of plagues and locusts! I'm sure I don't even need to mention which plague I'm talking about. But what about the locusts? Are you up on your entomological studies? Follow along, and see if you really know what locusts are... Locusts

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Analytics | Programming Tips

Rick WicklinJuly 7, 2021 0

Simulate multivariate correlated data by using PROC COPULA in SAS

In general, it is hard to simulate multivariate data that has a specified correlation structure. Copulas make that task easier for continuous distributions. A previous article presented the geometry behind a copula and explained copulas in an intuitive way. Although I strongly believe that statistical practitioners should be familiar with

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Programming Tips

Chris Hemedinger

Chris HemedingerJuly 6, 2021 0

How to work with emojis in SAS

Emojis are showing up in our data. Here's what you need to know when working with emojis in your SAS code.

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Learn SAS | Programming Tips

Leonid BatkhanJuly 6, 2021 0

Little known secrets of DO-loops with index variables

SAS' Leonid Batkhan reveals how to use versatile iterative DO loops with index variable pertaining to SAS DATA steps.

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Analytics | Programming Tips

Rick WicklinJune 30, 2021 0

Compute 2-D cumulative sums and ogives

A recent article about how to estimate a two-dimensional distribution function in SAS inspired me to think about a related computation: a 2-D cumulative sum. Suppose you have numbers in a matrix, X. A 2-D cumulative sum is a second matrix, C, such that the C[p,q] gives the sum of

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Programming Tips

Yinliang WuJune 25, 2021 0

How to evaluate SAS expressions in DATA Step dynamically

In many programming languages, there is a function named eval() that can be used to evaluate an expression and return the result at run time. For example, in Python, the eval() function parses the expression passed to it and runs a Python expression or code within the program. Even Python

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Programming Tips

Rick WicklinJune 23, 2021 0

The probability integral transform

This article uses simulation to demonstrate the fact that any continuous distribution can be transformed into the uniform distribution on (0,1). The function that performs this transformation is a familiar one: it is the cumulative distribution function (CDF). A continuous CDF is defined as an integral, so the transformation is

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Programming Tips

Peter Styliadis

Peter StyliadisJune 22, 2021 0

Getting Started with Python Integration to SAS® Viya® - Part 5 - Loading Server-Side Files into Memory

Welcome to the fifth 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, how to work with the results, and how your data is organized on the CAS server. In

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Programming Tips

Kevin RussellJune 21, 2021 0

Important caveats to consider when you run a DATA step on CAS tables

Kevin Russell of SAS Technical Support reveals the effects of data size and language elements in your code when you execute the DATA step in CAS.

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Programming Tips

Rick WicklinJune 21, 2021 0

The case of the missing blanks: Why SAS output might not show multiple blanks in strings

A SAS programmer noticed that his SAS output was not displaying multiple blanks in his strings. He had some strings with leading blanks, others with trailing blanks, and others with multiple blanks in the middle. Yet, every time he used SAS to print the strings to the HTML destination, something

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Programming Tips

Peter Styliadis

Peter StyliadisJune 17, 2021 0

Getting Started with Python Integration to SAS® Viya® - Part 4 - Exploring Caslibs

Welcome to the fourth 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 understand how your data is organized

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Data Visualization | Programming Tips

Robert AllisonJune 16, 2021 0

Don't let bad graphs undermine your credibility...

Having earned the Eagle Scout rank in Boy Scouts, I am of course very conservation-minded, and against polluting. I'm also an avid boat paddler and fisherman, and therefore I'm especially concerned about pollution in our rivers, lakes, and oceans. I even volunteered for a week to help survey coral reefs

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Learn SAS | Programming Tips

Leonid BatkhanJune 14, 2021 0

Using SYSTASK and SAS macro loops for massively parallel processing

SAS' Leonid Batkhan presents an implementation of parallel processing by spawning multiple SAS sessions using SYSTASK statements with subsequent synchronization.

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Analytics | Programming Tips

Rick WicklinJune 14, 2021 0

Simulate correlated variables by using the Iman-Conover transformation

Simulating univariate data is relatively easy. Simulating multivariate data is much harder. The main difficulty is to generate variables that have given univariate distributions but also are correlated with each other according to a specified correlation matrix. However, Iman and Conover (1982, "A distribution-free approach to inducing rank correlation among

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Data Visualization | Programming Tips

Robert AllisonJune 9, 2021 0

SEVENTY48: Seventy miles, in 48 hours

I've got this buddy, Carter Johnson - he's a little bit crazy, but a lot of fun to follow... He holds/held several different long-distance paddling world records, and was one of the coaches for the group that paddled kayaks from Cuba to the US (see my blog post). A few

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Sports & Entertainment

Analytics | Programming Tips

Rick WicklinJune 7, 2021 0

Permutation tests and independent sorting of data

For many univariate statistics (mean, median, standard deviation, etc.), the order of the data is unimportant. If you sort univariate data, the mean and standard deviation do not change. However, you cannot sort an individual variable (independently) if you want to preserve its relationship with other variables. This statement is

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Data Visualization | Programming Tips

Robert AllisonJune 2, 2021 0

Improving a population pyramid animation (Sweden, 1860-2020)

You've probably seen a population pyramid, such as this one I showed in a previous blog post. But let's scrutinize population pyramids a bit deeper, with an eye on special features that can make them even more useful! I was inspired to give population trees a second look by this

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Analytics | Programming Tips

Rick WicklinJune 1, 2021 0

The Hampel identifier: Robust outlier detection in a time series

It is well known that classical estimates of location and scale (for example, the mean and standard deviation) are influenced by outliers. In the 1960s, '70s, and '80s, researchers such as Tukey, Huber, Hampel, and Rousseeuw advocated analyzing data by using robust statistical estimates such as the median and the

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Analytics | Programming Tips

Rick WicklinMay 26, 2021 0

The running median as a time series smoother

When data contain outliers, medians estimate the center of the data better than means do. In general, robust estimates of location and sale are preferred over classical moment-based estimates when the data contain outliers or are from a heavy-tailed distribution. Thus, instead of using the mean and standard deviation of

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