DSCI 325: Handout 1 Introduction to SAS Programs Spring 2017

Transcription

1 DSCI 325: Handout 1 Introduction to SAS Programs Spring 2017 SAS (which originally stood for Statistical Analysis System) was started in 1976 and since this time has become an industry standard in the analysis of data. It is a fourth-generation programming language, and it was designed to reduce programming effort. It should be noted that SAS is much larger than data analysis. Some (potentially) useful links at SAS.com are given below RUNNING SAS STUDIO IN SAS UNIVERSITY EDITION Be sure that you have installed both Oracle VM VirtualBox and SAS University Edition on your machine. Once you have followed the instructions provided in the installation guide to start SAS University Edition (see the course website), you should see the following in your browser. Click Start SAS Studio to begin. You can enter SAS programming statements in the CODE tab. 1

2 THE SAS LANGUAGE A SAS program is a sequence of steps executed in order. The following is an example of a SAS program. Kilometers = 1.61 * Miles; SAS statements are individual commands that allow SAS to take a particular action. For example, in the above program, DATA, RUN, PROC PRINT, and QUIT are statements. As with many programming languages, there are syntax rules that need to be followed. One very important rule in SAS is that ALL SAS STATEMENTS MUST END WITH A SEMICOLON! There is not one best way to format your SAS statements and program; however, it is helpful to have a clean layout. SAS allows all of the following. o o o SAS statements are not case-sensitive (you can use either upper-case or lower-case) Statements can continue on the next line Multiple statements can be on one line Some things that SAS allows are not necessarily good. For example, the following program will work, but it is difficult to see the structure in this version versus the layout given above. Similarly, indenting and spacing between sets of statements are considered good programming habits. 2

3 No indents and spacing Good use of indents and spacing Kilometers = 1.61 * Miles; Inserting Comments: Another good habit is to add comments your program. Comments are items that SAS ignores (i.e., SAS will NOT read comments as statements). Comments can be created in two different ways: o To comment a single line, simply start the line with a * and end with a ; For example, consider the comment in the code below (which is colored green) * Creates a dataset containing Miles and Kilometers; Consider the following comment which does not contain the required semicolon * Creates a dataset containing Miles and Kilometers Question: What is the effect of the missing semicolon in the above comment? 3

4 o To comment multiple lines, a /* is used to begin a multiline comment and a */ is used to end such a comment. For example, using a /* at the start of the program and a */ at the end treats the entire program as a comment. The change of color to green signifies that these statements are being treated as a multiline comment. /* */ You can use the /* and */ method of commenting to place a comment anywhere in your program. Consider the following: /* This is a comment */ Or, you could add comments in the middle of a statement, as is shown here. PROC PRINT /* This is a comment */ DATA=distance; 4

5 PROGRAM HEADERS Program headers are comments at the beginning of a program that give information about that program. I encourage you to use program headers, as this is good programming practice. One example for a program header is given below, but feel free to get creative and develop your own style for your program headers. USING JUPYTER NOTEBOOKS WITH SAS UNIVERSITY EDITION What is Jupyter Notebook in SAS University Edition? 5

6 To write a new SAS program in Jupyter Notebook in SAS University Edition, you must first create a new notebook using the SAS kernel. From the Notebook dashboard, select New > SAS. A new Jupyter notebook file with an empty code cell opens in a separate browser tab. Enter your program in the code cell. To run the program and add a new code cell below the program, select the cell in the notebook and click the play button (you can also use one of the Run options from the Cell menu). If there are no errors, the results are displayed. 6