Valid GTL expressions
are identical to valid WHERE expressions. See the WHERE statement
documentation in Base SAS for a comprehensive list of operators and
operands. However, GTL expressions do not perform subset operations
as WHERE expressions do. The major difference in the result of a logical
GTL expression on a column is that a Boolean value is returned for
each observation without changing the number of observations.
For example, in the
following line of code, the expression for the Y= argument does not
reduce the number of observations plotted.
scatterplot x=name y=eval(height between 40 and 60);
Instead, the computed
numeric column for the Y= argument consists of 0s and 1s, based on
whether each observation’s HEIGHT value is between 40 and 60.
Whenever expressions are used to create new columns, a new column
name is internally manufactured so it does not collide with other
columns in use.