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Rick WicklinSeptember 6, 2012 0

Testing for equality of sets

Ah! The joys of sets! It is easy to test whether two vectors are equal in SAS/IML software. It is only slightly more challenging to test whether two sets are equal. Recall that A and B are equal as sets if they contain the same elements. Order does not matter.

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Rick WicklinAugust 20, 2012 0

How to return multiple values from a SAS/IML function

The SAS/IML language supports user-defined functions (also called modules). Many SAS/IML programmers know that you can use the RETURN function to return a value from a user-defined function. For example, the following function returns the sum of each column of matrix: proc iml; start ColSum(M); return( M[+, ] ); /*

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Rick WicklinAugust 16, 2012 0

Extract the lower triangular elements of a matrix

It is common to want to extract the lower or upper triangular elements of a matrix. For example, if you have a correlation matrix, the lower triangular elements are the nontrivial correlations between variables in your data. As I've written before, you can use the VECH function to extract the

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Advanced Analytics | SAS Events

Waynette TubbsAugust 10, 2012 0

Friday's Innovation Inspiration - Automated reports and poster ideas!

This Post-It Note reminds me of a presentation at SAS Global Forum 2012 about automating reports. Of course, these Post-It Notes always remind me of presentations. This week, instead of pointing you to a bunch of past presentations, I'm going to challenge you to use this note as an idea

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Waynette TubbsAugust 3, 2012 0

Friday's Innovation Inspiration - Ratemaking

In this Innovation Inspiration, a SAS user has developed the insurance rating plans for a country using predictive modeling. How exciting! Additionally, the system adjusts based upon actual experience. This is quite the accomplishment given the complexity of the ratemaking for even a small geographical territory. The comments section reveal the identity of this innovator. Check it out.

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Rick WicklinJuly 11, 2012 0

Visualize the bivariate normal cumulative distribution

When you are working with probability distributions (normal, Poisson, exponential, and so forth), there are four essential functions that a statistical programmer needs. As I've written before, for common univariate distributions, SAS provides the following functions: the PDF function, which returns the probability density at a given point the CDF

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Rick WicklinJuly 9, 2012 0

Reordering data to match a target order

Suppose that you have two data vectors, x and y, with the same number of elements. How can you rearrange the values of y so that they have the same relative order as the values of x? In other words, find a permutation, π, of the elements of y so

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Rick WicklinJuly 5, 2012 0

Compute the multivariate normal density in SAS

I've been working on a new book about Simulating Data with SAS. In researching the chapter on simulation of multivariate data, I've noticed that the probability density function (PDF) of multivariate distributions is often specified in a matrix form. Consequently, the multivariate density can usually be computed by using the

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Waynette TubbsJune 29, 2012 0

Friday's Innovation Inspiration - Extracting data from Oracle

It's so important for companies to build what customers want rather than build a product and then convince the market to buy it. So I love it when I hear or read remarks like the one below - SAS has grown with me. That means that we have listened to

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Rick WicklinJune 27, 2012 0

Create an ID vector for repeated measurements

I often use the SAS/IML language for simulating data with certain known properties. In fact, I'm writing a book called Simulating Data with SAS. When I simulate repeated measurements (sometimes called replicated data), I often want to generate an ID variable that identifies which measurement is associated with which subject

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Rick WicklinJune 22, 2012 0

Compute a running total for a "window" of time

A reader wrote for help with a computational problem. He has a vector of length N and the vector contains integer values in the range [1, 120], which represent months for which events occurred over a 10-year period. The question is: what is the 24-month period for which the most

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Advanced Analytics | SAS Events

Waynette TubbsJune 15, 2012 0

Friday's Innovation Inspiration - A billion rows on the fly

The first time that I saw a demonstration of SAS Visual Analytics Explorer was awesome, but it didn't give me goosebumps. I got goosebumps the size of golfballs during SAS Global Forum Opening Session when Dr. Goodnight sat down at a computer screen and began to demonstrate how effortlessly users can

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Advanced Analytics | Data Visualization | Programming Tips

Angela HallJune 12, 2012 0

How did you find that metadata?

A common question really and one that I get after posting code like yesterday's All SAS Stored Process Locations Report. The neat trick is just to type METABROWSE in a BASE SAS command window. (There are two other commands: METACON and METAFIND. Has anyone got any tips on when those

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Advanced Analytics | Data Visualization | Programming Tips

Angela HallJune 11, 2012 0

Where is the SAS code for that stored process?

Stored process code can exist within the metadata itself for version 9.3 (the benefits of which I discussed earlier). But for all other versions (and as a option in version 9.3) the SAS code is stored as a .sas file within the server's file system (or mapped folder/drive structure). When editing

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Advanced Analytics | Data Visualization | Programming Tips

Angela HallJune 8, 2012 0

Selecting multiple individual dates in prompted reports

The date prompt from SAS Prompt Framework provides the options of single selection or a range, however what if you need to select multiple individual dates such as Monday (May 28), Wednesday (May 30), and Friday (June 1) of last week? There are a few alternatives to accomplishing this. Option

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Advanced Analytics | Data Visualization | Programming Tips

Angela HallJune 7, 2012 0

Change your passwords without locking out your connection

Did you change your LinkedIn password yesterday? (If you didn’t, you should!) But did it happen to be the same as your corporate password? First, tisk tisk. Second, change your corporate password NOW! Ok, now that this is done ~ don’t let your saved connection profile for SAS applications lock

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Advanced Analytics | Data Visualization | Programming Tips

Open Stored Process GUI with Copy Selection

Angela HallJune 6, 2012 0

Backup or copy all components of your stored process before making changes

What if you would like to make a copy of an existing stored process to test out your changes before making them live? The copy command is available from within SAS Management Console or from the SAS Enterprise Guide Open Stored Process GUI as seen below (note you can only

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Advanced Analytics | SAS Events

Waynette TubbsJune 1, 2012 0

Friday's Innovation Inspiration - High-performance analytics with Jim Goodnight

One of the coolest things that I saw at SAS Global Forum was Dr. Goodnight dissecting a hologram of a SAS high-performance server and describing how the technology works with analytics. This is the height of innovation. You have got to watch this! Here are a few great

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Rick WicklinMay 29, 2012 0

Did you know that PROC IML automatically loads certain modules?

In the SAS/IML language, a user-defined function or subroutine is called a module. Modules are used to extend the capability of the SAS/IML language. Usually you need to explicitly load modules before you use them, but there are two cases where PROC IML loads a module automatically. Modules in IMLMLIB

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Waynette TubbsMay 25, 2012 0

Friday's Innovation Inspiration - Put up or shut up

Put up or shut up is one of those great sayings from my generation. Loosely translated it means, stop complaining if you aren't going to do something about the problem. In this week's Innovation Inspiration, the author decided to teach American middle schoolers how to question the information that they

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Rick WicklinMay 23, 2012 0

Compute statistics for each row by using subscript operators

In a previous blog, I showed how to use SAS/IML subscript reduction operators to compute the location of the maximum values for each row of a matrix. The subscript reduction operators are useful for computing simple statistics for each row (or column) of a numerical matrix. If x is a

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Advanced Analytics | SAS Events

Waynette TubbsMay 18, 2012 0

Friday's Innovation Inspiration - Jenine Milum creates a report

At SAS Global Forum, one of the most difficult areas for me to show to you are the poster presentations. This year, I asked Steve Polilli, a colleague who is great with a Flipcam, to video a few for me. I picked out three that I will use in the

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Advanced Analytics | SAS Events

Waynette TubbsMay 11, 2012 0

Friday's Innovation Inspiration - High schoolers analyzing high schoolers

Part of what captivated me about this paper and poster presentation were the presenters - these guys are high school kids using SAS to do a visual analysis of Internet use by high schoolers. The idea was so compelling that Anna Brown and Inside SAS Global Forum went to talk

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Rick WicklinMay 9, 2012 0

The power method: compute only the largest eigenvalue of a matrix

When I was at SAS Global Forum last week, a SAS user asked my advice regarding a SAS/IML program that he wrote. One step of the program was taking too long to run and he wondered if I could suggest a way to speed it up. The long-running step was

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Rick WicklinMay 7, 2012 0

Checking your answers: Are computed values close to the true values?

In statistical programming, I often test a program by running it on a problem for which I know the correct answer. I often use a single expression to compute the maximum value of the absolute difference between the vectors: maxDiff = max( abs( z-correct ) ); /* largest absolute difference

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Advanced Analytics | SAS Events

Waynette TubbsMay 4, 2012 0

Friday's Innovation Inspiration - A trend, fraud sniffer

Jenn Sykes (you probably remember her from this great sentiment analysis post last year about American Idol), presented Predicting Electoral Outcomes with SAS® Sentiment Analysis and SAS® Forecast Studio at SAS Global Forum 2012. In addition to predicting elections, Sykes tells Anna Brown from Inside SAS Global Forum, that there is a lot of unstructured data

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Rick WicklinMay 4, 2012 0

Expand data by using frequencies

A reader asked: I want to create a vector as follows. Suppose there are two given vectors x=[A B C] and f=[1 2 3]. Here f indicates the frequency vector. I hope to generate a vector c=[A B B C C C]. I am trying to use the REPEAT function

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Rick WicklinMay 2, 2012 0

The DIF function: Compute lagged differences and finite differences

To a statistician, the DIF function (which was introduced in SAS/IML 9.22) is useful for time series analysis. To a numerical analyst and a statistical programmer, the function has many other uses, including computing finite differences. The DIF function computes the difference between the original vector and a shifted version

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Rick WicklinApril 30, 2012 0

The LAG function: Useful for more than time series analysis

To a statistician, the LAG function (which was introduced in SAS/IML 9.22) is useful for time series analysis. To a numerical analyst and a statistical programmer, the function provides a convenient way to compute quantitites that involve adjacent values in any vector. The LAG function is essentially a "shift operator."

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