Suppose you have an old jalopy that's perfectly reliable. Your jalopy gets you where you wanna go: no frills; no drama. Do you trade your old wheels in for a racecar that accelerates like crazy and corners like it's on rails? Or stick with what's old and comfortable? Your choice
SAS macro variables are a great way to store a calculated value, so you can use it later in your code. They are not just limited to the data step -- you can also use macro variables in title statements, axis statements, etc. By default, the macro variable will be padded with
Many of my blogging colleagues are taking this week to reflect on their top posts in 2012. Some are using the visitor statistics to rank the posts, but as Andy Ratcliffe points out, that gives short-shrift to the late-season articles. This year, I'm going to use this space to recap
I used "Dropbox" in the title for this post, but these techniques can be used for other cloud-based file sharing services, such as GitHub and Google Drive. Using PROC HTTP (added in SAS 9.2), you can easily access any "cloud-based" file as long as you have a public link to
I was recently asked, "Does SAS support computing inverse hyperbolic trigonometric functions?" I was pretty sure that I had used the inverse hyperbolic trig functions in SAS, so I was surprised when I read the next sentence: "I ask because I saw a Usage Note that says these functions are
We are careening towards the holiday season, and this year more than ever before it's going to mean one thing: Online Shopping. As you enter your credit card number over and over to complete your many purchases, you might occasionally transpose or mistype your account number. Does it surprise you
I was looking at some SAS documentation when I saw a Base SAS function that I never knew existed. The NWKDOM function returns the date for the nth occurrence of a weekday for the specified month and year. I surely could have used that function last spring when I blogged
What's in a name? As Shakespeare's Juliet said, "That which we call a rose / By any other name would smell as sweet." A similar statement holds true for the names of colors in SAS: "Rose" by any other name would look as red! SAS enables you to specify a
According to the Daily Writing Tips blog, describing a thing as "somewhat unique" is bad form. Unique means "one of a kind", so either it is or it is not. The famous example (which the style police will use to chide you) is that you can't have something as "somewhat
Sometimes a graph is more interpretable if you assign specific colors to categories. For example, if you are graphing the number of Olympic medals won by various countries at the 2012 London Olympics, you might want to assign the colors gold, silver, and bronze to represent first-, second-, and third-place
SAS users world-wide have turned to Susan Slaughter, Lora Delwiche, and The Little SAS Book to learn SAS programming. This week's SAS tip is from their bestselling fourth edition of the book (the fifth edition is now available for preorder). Whichever version of The Little SAS Book you use, you'll benefit from the friendly
Regular expressions provide a powerful method to find patterns in a string of text. However, the syntax for regular expressions is somewhat cryptic and difficult to devise. This is why, by my reckoning, approximately 97% of the regular expressions used in code today were copied and pasted from somewhere else.
The project that I'm currently working on requires several input data tables, and those tables must have a specific schema. That is, each input table must contain columns of a specific name, type, and length in order for the rest of the system to function correctly. The schema requirements aren't
Sometimes a small option can make a big difference. Last week I thought to myself, "I wish there were an option that prevents variable labels from appearing in a table or graph." Well, it turns out that there is! I was using PROC MEANS to display some summary statistics, and
I've seen analyses of Fisher's iris data so often that sometimes I feel like I can smell the flowers' scent. However, yesterday I stumbled upon an analysis that I hadn't seen before. The typical analysis is shown in the documentation for the CANDISC procedure in the SAS/STAT documentation. A (canonical)
Last week I wrote an article in which I pointed out that many SAS programmers write a simulation in SAS by writing a macro loop. This approach is extremely inefficient, so I presented a more efficient technique. Not only is the macro loop approach slow, but there are other undesirable
Over the past few years, and especially since I posted my article on eight tips to make your simulation run faster, I have received many emails (often with attached SAS programs) from SAS users who ask for advice about how to speed up their simulation code. For this reason, I
No matter what statistical programming language you use, be careful of testing for an exact value of a floating-point number. This is known in the world of numerical analysis as "10.0 times 0.1 is hardly ever 1.0" (Kernighan and Plauger, 1974, The Elements of Programming Style). There are many examples
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
A colleague was recently working with a web service that supplies some datetime values using the Microsoft Windows internal representation. He called the web service to retrieve those values (along with other data) from SAS, and he needed convert these values to SAS date-time values. The Microsoft definition for a
I recently read a blog post in which a SAS user had to rename a bunch of variables named A1, A2,..., A10, such as are contained in the following data set: /* generate data with variables A1-A10 */ data A; array A[10] A1-A10 (1); do i = 1 to 10;
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
SAS software provides many run-time functions that you can call from your SAS/IML or DATA step programs. The SAS/IML language has several hundred built-in statistical functions, and Base SAS software contains hundreds more. However, it is common for statistical programmers to extend the run-time library to include special user-defined functions.
Last week I blogged about how to construct a smoother for a time series for the temperature in Albany, NY from 1995 to March, 2012. I smoothed the data by "folding" the time series into a single "year" that contains repeated measurements for each day of the year. Experts in
In yesterday's post, I discussed a "quick and dirty" method to smooth periodic data. However, after I smoothed the data I remarked that the smoother itself was not exactly periodic. At the end points of the periodic interval, the smoother did not have equal slopes and the method does not
Over at the SAS and R blog, Ken Kleinman discussed using polar coordinates to plot time series data for multiple years. The time series plot was reproduced in SAS by my colleague Robert Allison. The idea of plotting periodic data on a circle is not new. In fact it goes
Over at the SAS Discussion Forums, someone asked how to use SAS to fit a Poisson distribution to data. The questioner asked how to fit the distribution but also how to overlay the fitted density on the data and to create a quantile-quantile (Q-Q) plot. The questioner mentioned that the
Locating missing values is important in statistical data analysis. I've previously written about how to count the number of missing values for each variable in a data set. In Base SAS, I showed how to use the MEANS or FREQ procedures to count missing values. In the SAS/IML language, I
Earlier this week I described a common programming pattern in the SAS macro language. The pattern sets up a loop for processing each distinct value of a classification variable. The program uses the PROC SQL SELECT INTO feature to populate SAS macro variables. The effect: you can roll your own
How to write a SAS macro program to repeat your SAS processing for each value of a BY grouping variable.
