Using do statements, links, and arrays sas support. The main reason is that you can usually reach the same result without them. Below, we run a regression model separately for each of the four race categories in our data. Some languages support a foreach loop that iterates over objects in a collection. However, the question was how to loop over a list and a proc statement in general. An introduction to macro variables and macro programs mike s. We will look at many examples, including 1 input and output of files. The for statement includes the three parts needed for loops. Zdeb, new york state department of health introduction there are a number of sas tools that you may never have to use. Looping a job in di studio to take a series of sna. The whitlock sub setting loop also known as the do whitlock dow loop and doubledow are illustrated. In the example above, if we check the loop by printing 1 star, instead of 10 by substituting 10 with 1 in the condition of the loop, we immediately notice that the loop would print 2 stars, instead. Aug 08, 2016 good post on a very useful sas feature rick.
Using the iterative do statement without infinite looping. In this example, we told sas to execute the loop while loan is equal to zero. Overview some loop processing algorithms require either a skip pattern or a conditional exit. Do loops and the set point option to randomly select a specific number of records from. She wanted to display formats such as dollar for some variablesbut only for certain statistics. Proc ds2 is a new sas proprietary programming language with full release. Then when you create a sas data set, the data set variable automatically gets the same format.
The basic iterative do statement in sas has the syntax do value start to stop. Nesug 15 applications development sas proceedings and more. The syntax in the data step is to specify a list of values numeric or character after the equal sign. Nov 08, 2017 for example, the number of nonmissing observations n should never use the format of the variable, whereas the minimum, maximum, and mean values should. For example, the following code reads each row in the dept table, and if the status is not pt, it displays a frame that. In the previous example, that value of country is included. This paper presents a number of examples to demonstrate how to take advantage of the %do loop to build sas statements dynamically. Sas do index loop this do index loop uses a index variable for its start and end value. A sas programmer wanted to display a table in which the rows have different formats. In sas you can easily apply a format to a column, but not to a row. Sas arrays will also be discussed for handling the most complex form of do. A data step or procedure in base sas is ended with a run statement.
This example uses a length statement to set the length of the character variable name to 25 bytes. Lets take a look at the general form of iterative do loops. Question on referencing do loop variables as macro. Increment cannot be manipulated by logic inside the loop. Import or create a table of parameters dates to loop over. Sep 07, 2011 older languages, such as fortran and sas, call the iteration statement a do loop, but it is exactly the same concept. Running the same procedure against a series of data sets in previous examples, the %do loop is used to generate single sas statements. The following program uses a do loop to tell sas to determine what four times three 4. The continue statement stops the processing of the current do loop iteration and resumes with the next iteration of the loop. Functions that create sas date, datetime, and time values the first three functions in this group of functions create sas date values, datetime values, and time values from the constituent parts month, day, year, hour, minute, second. This example demonstrates using the %do %while to strip markup sgml tags from text to create a title. The do statement designates a group of statements that are to be executed as a unit, usually as a part of ifthenelse statements.
A quick intro to sas arrays and do loops gopinath narasimhan saskatchewan cancer agency march 12, 2014. The length statement also changes the default number of bytes that sas uses to store the values of newly created numeric variables from 8 to 4 bytes. Sas loops you may encounter situations, when a block of code needs to be executed several number of times. When contents of the same group variables carry to the following page, the group variables do not display. The control table contains the values which you want to pass to the inner job as parameters via prompts so the inner job gets the values in macro variables. Beside export there are also other use cases for example caculating statistics for serveral subsets of a data set. Connect the table of parameters to a loop transformation, connect the parameterized job to the right end of the loop transformation, and connect the right end of the parameterized job to a loop end transformation. Here is an example usage of loop transformation which is different from the one mentioned in the sas di studio documentation and is relevant to your problem. All this information is conveniently placed at the beginning of the loop. The do loop seems to be the solution but didt work exactly as i want.
Using a format after calling the makeform macro or using proc format, the format can be used as needed. A benefit in using a userdefined format is simpler management of your business definitions. This paper presents a simple dynamic programming technique, the %do loop. Together they allow us to iteratively process large amounts of data with a minimum amount of code. For example, a data step will be compiled and executed, then a procedure step will. This is necessary since, if sas reads in any endoffile marker, the data step closes.
A vector of dates records when the heights were measured, and a vector of percentiles indicates how the childs height compared to the heights of his peers. 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. Arrays are sas data step statements that allow iterative processing of variables and text. The iterative do statement executes a group of statements repetitively based on the value of an index variable. Examples of do loops in sas with proc ds2 quanticate. If indexvariable is still in the range between start and stop, then if you specify an until clause, the do group will execute until the until expression is true.
This implementation of the macro %do loop works perfectly fine, except in the situations when we need to use it within a dataproc step. Sas doesnt support that syntax directly, but there is a variant of the do loop in which you can iterate over values in a specified list. No group line from the second to last page pdf sas 8. Nov 29, 2017 sas iml software and matrix computations. I create macro variables containing the data i want for each scenario. Since loan is equal to 30000 at the start of the program, the loop does not execute at all the loan and payment values remain unchanged.
The sas statements are repeatedly executed until the final value of the index variable is. Its not a very useful way of manipulating dates like this in sas but if youre just doing it to learn sas then can put them in a do loop with a two dimensional array. The preprocessor reads through the whole program, one or more times, converting macro code into text strings. A while expression is evaluated before each execution of the loop so that the statements inside the group are. The statements in a do until loop are always executed at least once, but the statements in a do while loop will not execute even once if the do while expression is false.
The sas statements are repeatedly executed till the until condition becomes true. The following example iterates over a few terms in the fibonacci sequence. Examples of such tools are arrays, macros, and quite possibly proc sql. Sep 07, 2011 some languages support a foreach loop that iterates over objects in a collection. The point is i have to use the last observations data to compute the lagged variable for the next observation. Proc sql concat numbers in sas and format as date sas e guide 5. Using macro variables within a cards or datalines statement tree level 3. For loops carnegie mellon school of computer science. To avoid such types of errors, it is often convenient to test the loop with simple i. This code is more dynamic than the previous example with the hard coded number of repetitions. In each of the following examples, the do group executes ten times. An end statement marks the end of the loop, as shown in the following example. How can i generate pdf and html files for my sas output.
The loop transformation then executes the inner job once per row in this control table. Lets look at a couple examples where a basic iterative do loop can be used. The output statement tells sas to output the value of the index variable i for. These should be character representations of dates.
Jun 02, 2014 then when you create a sas data set, the data set variable automatically gets the same format. Use sas formats to bin numerical variables the do loop. A beginners guide to arrays and do loops sas institute. Heres the simple syntax of the do statement, with descriptions. Writing cleaner and more powerful sas code using macros myweb. As an example, the following sasiml program defines data for the height of a hypothetical child. Variables in a list for example, in a select statement in proc sql are separated with a comma between each variable. Sas do until loop the do until loop uses a until condition.
This is not obvious because the syntax requires both verbs to come after the. By testing for done at the top of the loop do while, and exiting the do loop after the last line of every file, we ensure that we never hit the endoffile for all files read in. The do while statement executes statements in a do loop repetitively while a condition is true, checking the condition before each iteration of the do loop. Nesug 15 applications development sas proceedings and. This implementation of the macro %doloop works perfectly fine, except in the situations when we need to use it within a dataproc step. The programmer wanted columns that represent statistics and rows that represent variables. Im searching for a while an equivalent of the for in loop like in python or in r in sas 9. If you specify an until clause or a while clause, then the execution of the. Then it processes the global statements, data steps and proc steps, as you would expect in any sas program which did not have macro code in it. The endpoint parameter is a list of the endpoints for each level of the format.
The sas statements are repeatedly executed until the while condition becomes false. 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. Sas do while loop this do while loop uses a while condition. If the condition is false the first time the macro processor tests it, the %do %while loop does not iterate. In this example, the second region spans two columns. In the simple example given above, an array would definitely work. Question on referencing do loop variables as macro variables in a datastep posted 10082015 510 views hi. I founded a way to do it in a data step with a do loop but it dont work with the macro language.
In base sas code, they are only separated with a space. Working in di studio, ive created a job that takes a snapshot from the end of a month using the intnx function. However, sas provides two techniques that enable you to control the appearance of cells in tables. This example shows how to use macro logic and a macro %do loop to loop through a starting and ending date. Sas arrays a sas array is a set of variables of the same type, called elements of the arry, that you want to perform the same operation on. How to make a sas dis job loop over rows of a parameter table. Sas macro, including macro arrays, and build to more complex examples. On the second iteration of the data step loop, the set statement tries to read a fifth record and hits the end of file so the data step completes. You can use the continue and leave statements to control the flow of execution through do loops. However, without some proper training it is difficult to implement, or when it is implemented it often results in hard to understand code.
The for loop another loop statement, for, is best for when you can determine in advance how many times you need to execute the loop counting loop. If the parameter is set to 1, the job creates a snapshot of the previous month august. 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. I want to loop through every csv file in a folder, delete the first two line of each csv file, and save each csv file as a sas data in sas 9. Arrays and do over loops are a way of programming more. If you have your format definitions centralized, and a change is required due to business reasons. So i want to reference a sas do loop variable as a macro variable, so that i can call different variables within the dataset based on what the loop variable is. In a more dynamic solution, the program should include code to determine the number of repetitions. Most of the time simply putting the macro variable in the code will suffice. Many sas data step functions like put have macro analogs. If we were in the ith iteration of a loop, how would. In this example, the do loop is executed when i1 and i2. Chapter 9 working with the loop transformations sas.
Example 2 generating records with an incremental do loop in addition to calculating a final number, a do loop can be used to generate records, storing the result of each iteration in a new record. Example this example uses the %do %until statement to scan an option list to test the validity of the parameter type. But on the first iteration of the implicit data step loop, you execute the set statement four times inside the explicit do loop, reading all four records. The %do %until statement checks the value of the condition at the bottom of each iteration. Carpenter california occidental consultants, anchorage, ak abstract do loops and array statements are common tools in the data step. The %do %while statement tests the condition at the top of the loop. Loop through dates using a macro %do loop tree level 3.