How old is sas programming

The Results window enables you to view a list of results from executed SAS programs. In SAS 9. Specific options are invoked by default when you open SAS. The options can vary depending what computing environment you are using e. Windows, Unix. SAS includes two types of options: portable and host. Portable or nohost are options that are the same regardless of the operating system.

Host options are different depending on which operating system you are using. When the option is invoked, you will see that in the Log shown below , SAS issues a warning it assumed that the keyword was misspelled and continues executing the procedure. However, in the second example where the automatic correction option is turned off, SAS issues an error and stops executing the procedure.

In this case, the default is for SAS is to error and stop processing the executed procedure. In the first example, the default option is invoked and as you can see below SAS issues a warning that the format used could not be found.

A main issues with learning a new programming language is the ability to identify and address coding errors. There are several ways that SAS will notify you of syntax errors.

Color coding program components will help you more easily diagnose syntax errors, and when you first start with SAS you will make many mistakes. Take a look at the example syntax below copied from the Enhanced Editor window. Here you will see 5 different colors automatically generated by SAS. If you use the wrong keyword with a procedure, the keyword will often remain black like the variable names because SAS does not recognize it.

As we will discuss later, the way to indicate a format is to put a period at then end and, once you do this, it will turn green. Anything in quotation marks turns red. In the second set of code, you will see that we are missing an end quote, thus all of the syntax is red. Thus we would know to correct the missing double quote. The log file will also let you know when you have syntax errors. Below we see what happens when we attempt to execute the syntax as written. Additionally, in this instance, SAS provides a list of alternate options you may have wanted.

SAS programs are comprised of two distinct steps: data steps and proc steps. Data steps are written by you, while procedures are pre-written programs that are built-in. You saw an example of a data step in section 1.

From a statistical standpoint a Proc step is typically used to analyze a dataset in SAS without making changes to the data. There are exceptions to this. Each procedure enables us to analyze and process that data in specific way. An operator in SAS is a symbol representing a comparison, logical operation or mathematical function.

These are operators that compare a variable with some specified value or another variable. The operators can used within a data or proc step depending on your needs. The IN operator can be used if you are trying to specify a list or range of values, as demonstrated below. We also can specify SAS to output only certain ranges of values for numeric variables. One limitation of using a WHERE statement is that more than 1 can not be used simultaneously, except in special cases.

However, in the next section we will demonstrate how to combine comparison operators with logical operators to achieve the desired output. For more example checkout SAS 9. They are often used to link a series of comparisons. Just like the comparison operators, these can be written as either symbols or mnemonics. In the previous section we learned that we cannot use two WHERE statements, but we can use the AND operator to combine the information contained in those two statements to achieve the desired result.

Both the symbol and mnemonic are used and they give the same result. We have just covered several examples using the comparison and logical operators. Some of these have similar functions to comparison operators. Char or Num. Is Null or Is Missing. As in any good programming language, there are always multiple ways of doing the same thing. These will allow you to update or augment an existing WHERE statement to add an additional conditions.

These operators can be helpful for identifying issues such as misspelled information, incorrectly entered information, or identifying related names or titles that vary. How could we do that? It works by comparing character values to some given pattern. The percent denotes that any number of characters may occupy a position. However, the underscore specifies that only one character may occupy a position. Arithmetic operators, as you can probably tell from the name, allow you to perform arithmetic calculations in SAS.

Below is a table of the operators and their symbols used in SAS. A few things to note about using these operators. First, if you are calculating values using a variable s with missing data, the resulting value will also be missing.

This ordering can be modified by using parentheses. Third, as is the case with the other operators we have discussed, arithmetic operators can be using on conjunction with both logical and comparison operators. We will use a Data step to create two new variables profit1 and profit2. Conditional processing in SAS allows the user to manipulate and output portions of data instead of the whole file. This indicates that the syntax is incorrect. Below is an example of an assignment statement.

Can you think of equivalent ways of subsetting the data? Moreover, you will notice that SAS allows you to create a variable and use it in an IF statement in the same Data step. The reason for this has to do with when SAS executes conditional statements. This makes for more efficient processing of data especially with large amounts of data. However, IF conditions are not processed until the end of the Data step. An If-then statement is a commonly used assignment statement that is typically carried out within the context of Data Step.

It executes a SAS statement that fulfills a certain condition. You will see in the output above, that several observations have missing values. SAS process the first IF statement and if it is not true it moves to the next and so on. Once again, this can speed up the processing of large datasets. However, as was the case with the first IF-THEN example, we will end up with a lot of missing values using this syntax. What if we had a scenario where we wanted to give all the remaining categories, that did not fulfill the prescribed conditions, one bonus value.

In the example below, we delete all observations associated with three specific job titles. When an expression is true the associated statement is executed. But what happens if you want more then one statement executed for each expression. So we might try the following code using a logical operator. You could try this:. You are probably thinking about 5. SAS 5. People have written SAS macros that try to automate this process. Pingback: When did you first use SAS?

Pingback: 13 popular articles from - The DO Loop. Just what I was looking for, Rick. And from your later follow-up, I can see that I got on board with version 6. Save my name, email, and website in this browser for the next time I comment. Date DATE9. Tags Michelle Homes on August 2, am. Peter Lancashire on August 2, am. Robby Powell on August 8, am. Rick Wicklin on May 30, am. Jiangtang Hu on August 6, pm.

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Rick Wicklin on August 15, pm. Loch Macdonald on April 18, pm. Rick Wicklin on April 19, am. It is also possible to take an existing data set and create a new data set with additional variables, instead of inputting the data anew.

We first create a copy of the data set using the set statement, and then make changes in the data step. Because the data set weight already exists within SAS, no input statement is necessary. The log will always show you your code and then log notes and warnings and errors. From now on, we will only show the actual log not the code. In order to create a new variable in an existing SAS data set, the data set must first be read into SAS and then a data step must be used to create a new SAS data set and the new variable.

The following data step creates a new temporary SAS data set called bmidata, which is identical to the SAS data set weight but with the addition of a new variable bmi. We can also create a new data set from an already existing permanent SAS data set. We first import the permanent SAS data set in the C: directory called weight. Next, we will import the permanent SAS data set weight. Note that we do not have to include the libname statement again since we have already done so above in the same SAS session.

An if-then statement can be used to create a new variable for a selected subset of the observations. For each observation in the data set, SAS evaluates the expression following the if.

When the expression is true, the statement following then is executed. When the expression is false, SAS ignores the statement following then. For a person whose age is less than 65, the variable older will be missing. An optional else statement can be included if-then-else to provide an alternative action when the if expression is false. An optional else-if statement can follow the if-then statement. SAS evaluates the expression in the else-if statement only when the previous expression is false.

Note that this if-then-else-if statement could equivalently be written. An if statement can be followed by exactly one else statement or by many else-if statements. SAS will keep evaluating the if-then-else-if statements until it encounters the first true statement. The following code creates a new variable called group from an existing variable called gpa. The new variable called group takes on one of two values: "good standing" if a person's gpa is greater than or equal to 3.

Ann 3. Bart 2. Cecil 3. Denise 4. Emily 2. Frank 3. Note that SAS does not generally distinguish between upper and lower case you can use either. The exception is in the value of character variables.

The value "Good standing" is not the same as the value "good standing". SAS code follows the rules of logic: SAS evaluates if-then statements in the order in which they appear in the datastep. What went wrong? We should instead use if-then-else statements as follows:. If we run proc means , we would get the following:. SAS will automatically exclude missing values from calculations, if they are coded correctly.

However, some data sources will code missing values as 9 or -9 or 99, or some other numeric value. If this is the case, you should immediately re-code these to periods.

If you don't recode the missing values, here is what will happen:. If we run proc means, we would get the following:. Notice that the minimum age is negative! And the mean age is less than the youngest age in the data set.