WHERE operators in SAS: Multiple comparisons and fuzzy matching

The WHERE clause in SAS is a powerful mechanism for selecting observations as you read or write a data set. The WHERE clause supports many operators, including the IN operator, which enables you to compactly specify multiple conditions for a categorical variable. A common use of the IN operator is to specify a list of US states and territories that should be included or excluded in an analysis. For example, the following DATA step reads the Sashelp.Zipcode data, but excludes zip codes for the states of Alaska ("AK"), Hawaii ("HI"), and US territories such as Puerto Rico ("PR"), Guam ("GU"), and so on: In my previous article about how to use the WHERE clause in SAS/IML, my examples used scalar comparisons such as where(sex "F") to select only females in the data. The SAS/IML language does not support the IN operator, but there is another compact way to include or exclude multiple values. Because SAS/IML is a matrix-vector language, many operations support vector arguments.