Do until loops continue executing until the condition you have specified becomes true. I was given the additional statement, the % do loop isnt within a create table command. Sas performing loops in a proc step stack overflow. The difference between the loops is based on the fact that the do while loops continue executing until the condition for the loop is true, whereas the do until loop will execute till the specified. A beginners guide to arrays and do loops sas institute.
Included are examples of do and array statement shortcuts. Do loop, do until, dow loop, array statement, dim function, set statement options introduction although most sas data step programmers have made use of do loops and arrays, few take full advantage of the power and flexibility of these tools. The set of variables is then referenced in the data step by the array name. K3 do iterate compare the iteration with the do until and do while examples above. Resolving macro variables in quotes within proc sql passthroughs. When coupled with a sas array, do group processing simplify the data manipulation process even further. Examples of do loops in sas with proc ds2 quanticate. It is hidden in the do l statement, line 21, and happens between lines 22. How to use character values on a macro %do loop sas. His areas of expertise include computational statistics, simulation, statistical graphics, and modern methods in statistical data analysis. One often uses an iterative % do loop to execute a section of a macro repetitively. Sas arrays a sas array is a set of variables of the same type that you want to perform the same operation on.
I have a list of variables i want to do a proc summary on. It discusses statistical and computational algorithms, statistical graphics, simulation, efficiency, and data analysis. Fehd, centers for disease control, and prevention, atlanta, ga, usa abstract the sasr macro language is simple, yet powerful. Loops in sas different loops in sas with their examples educba. Select variables to transpose with the var statement. Sas programmers often need to create labels for a numbered series of variables with a common prefix. Use do loops to eliminate redundant code and to perform repetitive calculations. List processing with proc sql is also simple, yet powerful. This paper demonstrates how to use macro nested macro call, %do %until loops and ods output delivery system to create an automated backward model selection process for proc genmod which does not come with model selection. The do statement, the simplest form of do group processing, designates a group of statements to be executed as a unit, usually as a part of ifthenelse statements. Given below is the general form of a do loop statements in sas. But when you want the same set of statements to be executed again and again, we need the help of loops. Do loop do loops are executed usually repeatedly according to directions that are specified in the do. Rick wicklin, phd, is a distinguished researcher in computational statistics at sas and is a principal developer of proc iml and sasiml studio.
As these proc summaries are performed individually per variable, it would be faster for me if i can find some way to loop through a numbered list of variables, then create an output to excel or simply a combined table of results that clearly indicates what results belong to what variable. Posted 04082010 1624 views in reply to qli sort your input data, then in a data step, assign a new sas variable with an incrementing value to represent each unique grouprange, and each time the current observation has exceeded your previous grouprange, increment the new variable. Do while loops continue executing while the condition you have specified remains true. Writing cleaner and more powerful sas code using macros myweb. Im new to sas, and im having trouble with do loops.
It is understandable that some programmers look at the simulation algorithm and want to write a macro loop for the repeat many times portion of the algorithm. Arthur li, city of hope national medical center, duarte, ca. How can a beginning sas programmer write less sas code for this type of data preparation that is also more efficient. Sas do while loop this do while loop uses a while condition. May 11, 2020 rick wicklin, phd, is a distinguished researcher in computational statistics at sas and is a principal developer of proc iml and sas iml studio. Jun 05, 2019 rick wicklin, phd, is a distinguished researcher in computational statistics at sas and is a principal developer of proc iml and sas iml studio.
Do loops in sas iml software a basic iterative do statement in the sas iml language has exactly the same syntax as in the data step, as shown in the following proc iml statements. Question 2 open a new programming window to create mac01. For example, in scl programs, you can use do loops, ifthenelse statements, comparison operators such as eq and lt, and sas macros. The do until statement executes statements in a do loop repetitively until a condition is true, checking the condition after each iteration of the do loop.
You can also iterate backwards by using a negative value for the by option. This paper presents a simple dynamic programming technique, the %do loop. The sas statements are repeatedly executed until the while condition becomes false. Interactive procedures remain running until you submit a quit statement, or until you submit a new proc or data step. Department of commerce abstract boilerplate sas programs are real time savers, but frequently input datasets have different variables and values not accounted for in the code. Arrays and do loops are efficient and powerful data manipulation tools that you should have in your programmers tool box. You could also do it in graph template language, dynamic variablesconditional templates which for this example might be a bit overkill, but it is well worth learning for more complicated graphs, good help is. Sas do loops in proc ds2 proc ds2 is a new sas proprietary programming language with full release in version 9. An alternative method is to utilize the implicit loop in the data step with the execute routine to generate a series of macro calls.
A neat feature of arrays is that sas can count the number of variables. Fehd, centers for disease control, and prevention, atlanta, ga, usa. But you can use the % do loop in a macro like the following to accomplish this. Arrays and do over loops are a way of programming more. Sas do loop sgplot posted 01262018 1024 views in reply to anlyng if you change your sgplot procedure to use a by statement you can use the newfile option on the ods pdf statement to generate a new file for each by group. These are basically two loops which are do while and do until. Proc iml is unusual in that you do not need a run statement in order to execute sasiml statements. Using do loops there are four forms of the do statement. The do statement designates a group of statements that are to be executed as a unit, usually as a part of ifthenelse statements. I was given the additional statement, the %do loop isnt within a create table command. The until test is evaluated at the bottom of the loop.
The do statement, the simplest form of dogroup processing, designates a group of statements to be executed as a unit, usually as a part of ifthenelse statements. A typical sas program can be divided into two steps namely the data step and proc step. We use a do loop to perform the data manipulations on the arrays. It discusses statistical and computational algorithms, statistical. The other type of do loops that you can run in a sas data step are conditional do loops. In the example above, sas would automatically calculate the number of variables in array. Carpenter california occidental consultants abstract one of the unique features of the report procedure is the compute block. A quick intro to sas arrays and do loops gopinath narasimhan saskatchewan cancer agency march 12, 2014. Do loop processing do loop processing statements within a do loop execute for a specific number of iterations or until a specific condition stops the loop. Data statement sas statements do statement iterated sas statements end statement sas statements run statement do loop processing you can use do loops to perform repetitive calculations. Where the x1 variable contains the x1 value, x2 contains the x2 value, etc. Although most sas data step programmers have made use of do loops and arrays, few. To check that the new variables were created, we run a simple proc contents after the data step. Avoid unnecessary loops in the sasiml language i have some advice on using do loops in sasiml language.
Unlike most other sas procedures, proc report has the ability to modify values within a column, to insert lines of text into the report, to create columns. It enables you to loop over unique values of a categorical variable in this case, unique cities and do something for each value in this case, copy the distance into another array. For example, price2 in observation 5 will now be 126. Sas do loops so we have now defined our array, but now we have to use it to manipulate the data. Simplifying your %do loop with call execute sas support. Sas arrays and macros make processing claims with multiple. Do loops in proc ds2 fred ross, quanticate international ltd, manchester, united kingdom george allerston, quanticate international ltd, manchester, united kingdom rachel linacre, quanticate international ltd, hitchin, united kingdom abstract proc ds2 is a new sas proprietary programming language with full release in version 9. Loops in sas different loops in sas with their examples. Also, since sas dataset names can only contain alpha, numeric and underscore characters, rather than try to create an illegal name that contained a. Since macro do loops cant handle fractions, i used 100 to 200 by 25, rather than 1 to 2 by. The iterative do statement executes a group of statements repetitively based on the value of an index variable. For most interactive procedures, you execute statements by submitting a run statement. Sep 07, 2011 avoid unnecessary loops in the sas iml language i have some advice on using do loops in sas iml language.
I have some advice on using do loops in sas iml language. Top 50 sas interview questions for 2020 sas training edureka. Do loop proc freq posted 091720 2687 views in reply to hsharma i would look at the table in sashelp. Learn how to use doloop, dowhile and dountil in sas. The do until statement executes statements in a do loop repetitively until a condition is true. Do group a do group is a sequence of statements that starts with a simple do statement and that ends with a corresponding end statement. The sas iml language is a matrixvector language, so statements that operate on a few long vectors run much faster than equivalent statements that involve many scalar quantities. Lets look at a couple examples where a basic iterative do loop can be used.
There are many variations of the do statement and these can be used in. The sasiml language is a matrixvector language, so statements that operate on a few long vectors run much faster than equivalent statements that involve many scalar quantities. Within a data step, a do loop is used to specify a set of sas statements or operations that are to be performed as a unit during an iteration of the loop. Arrays list the variables that you want to perform the same operation on and can be specified with or without the number of elementsvariables in the array. Using the count function with a do loop in the data step to create a sas data set consisting of programming language, and the. The technique you want to use is called the uniqueloc technique. We will look at how useful this can be in some of the examples later in this paper. If you have experience writing data or proc steps in the base sas language, the basic elements of scl are familiar to you. Proc iml is unusual in that you do not need a run statement in order to execute sas iml statements. There are two forms of conditional do loops, do until loops and do while loops. Dec 12, 2011 proc iml is also an interactive procedure. I have some advice on using do loops in sasiml language. The data step retrieves and helps in the manipulation of the data. Do loopsdo loops are used when a statement or set of statements needs to be repeated many times.
Conditional loops in sas are the other do loops that are executed over in data steps. Jul 18, 2012 you can program this simulation in two ways. Sep 07, 2011 avoid unnecessary loops in the sas iml language. All price values for all price1through price17 will be increased by 10%. In previous examples, the %do loop is used to generate single sas statements. The % do loop is replaced with a sequence of text that follows the create table command. How to prepare for the sas certified specialist base programming exam. To have sas do the counting, put a in the brackets instead of the number of elements. Do you often need to transpose your data sets from long multiple rows per subject to wide multiple columns per subject.1248 374 1146 941 927 98 1563 899 419 866 761 603 387 743 1583 608 1513 481 834 574 613 208 694 521 839 192 978 1292 1204