Using Workspace Objects in Expressions

You can use objects in expressions as described below:

• You can use a dimension, a dimension surrogate, a relation, or a variable as an array of data by specifying the name of the object.
• You can use a formula or a function as a sub-expression or as an expression in a command or function by specifying the name of the formula or the function.
• You can use a valueset as a list of dimension values in an expression by specifying the name of the valueset.
• You can use various data objects as the target or source expression in an assignment statement.

Using Dimensions or Dimension Surrogates in Expressions

In expressions, a dimension or dimension surrogate is referenced as a one-dimensional array.

If the dimension or surrogate has a data type of TEXT, then, in most cases, its values are referenced as text values. NUMBER dimension values are always referenced by the value itself.

However, for dimension types other than NUMBER dimension values are referenced by their numeric positions in the dimension array when you do one of the following:

• Use a dimension with a data type of TEXT in a numeric expression
• Compare one value in a dimension to another value in the same dimension

In these cases, the integer position number is based on the default status list, not on the current status.

Using Composites in Expressions

In expressions, composites behave much the same way that dimensions do and, generally, you can use a composite in an expression anywhere you can use a dimension:

• If the composite is named, then specify its name.
• If the composite is unnamed, then specify SPARSE <dimensions...>.

Using Variables in Expressions

In expressions, a variable is referenced as an array containing values of the specified data type.

When you assign values to a variable or when you use REPORT or another command or function that loops over the dimensions of a variable, the values of the fastest-varying dimension of the variable vary first. For example, for the opcosts variable that is dimensioned by month and city, when you view the variable as REPORT command output, you see the data for all months for the first city before you see any data for the second city. In this case, month is the fastest-varying dimension because its values change before those of city. When you write programs that loop over a multidimensional variable in this way, try to maximize performance by matching the fastest-varying dimension with the inner loop.

You can uniquely and completely select any item of data within a multidimensional variable by using a qualified data reference (QDR) to specify one value from each of the dimensions of the variable.

For example, if the opcosts variable is dimensioned by month and city, specifying 'JAN02' for the month dimension and 'BOSTON' for the city dimension uniquely specifies a single cell in the variable.

Using Variables Defined with Composites in Expressions

In most cases, when you use functions and commands with variables that are defined with composites, the functions and commands treat those variables as if they were defined with base dimensions:

• You can access a variable that is dimensioned by a composite by requesting any of the base dimension values.
• The values of a composite that are in status are determined by the status of the base dimensions of the composite. Composites are not dimensions, and therefore, they do not have any independent status.

Default Behavior of Commands That Loop Over Variables

When you use the REPORT command or any other command that loops over a variable that uses a composite, the default behavior is to evaluate all the combinations of the values of the base dimensions of the composite that are in status. Any combinations that do not exist in the composite display NA for their associated data.

For example, the following commands create a report for the East region that shows the number of coupons issued for sportswear from January through March 2002. Since no coupons were issued in March 2002, the report displays NA in that column.

LIMIT month TO 'JAN02' 'FEB02' 'MAR02'
LIMIT market TO 'EAST'
LIMIT product TO 'SPORTSWEAR'
REPORT coupons
  
MARKET: EAST
               ------------COUPONS-------------
               -------------MONTH--------------
PRODUCT          JAN02      FEB02      MAR02
-------------- ---------- ---------- ----------
SPORTSWEAR          1,000      1,000         NA

However, for performance reasons, you can change the default looping behavior for commands such as REPORT, ROW, and = so that they loop over the values in the composite rather than all of the base dimension values.

Using Relations In Expressions

A relation is, in many ways, just a special type of variable. Instead of holding general data values, a relation contains values of the related dimension. Consequently, in an expression, a relation behaves somewhat like a variable and somewhat like a dimension:

• When you use a relation in a text expression, the relation value is referenced as a text value. The values of the related dimension that is contained in the relation are converted into text, and you can use these values in an expression. You can also compare a text literal to a relation.
• When you use a relation in a numeric expression, the relation value is referenced by its position (an integer) in its related dimension array. You can use this numeric value in an expression. The position number is based on the default status list of the dimension, not the current status list of the dimension.

Using Functions in Expressions

A function is a predefined calculation that returns a value. A number of built-in functions are provided, including:

• Numeric functions. You can use these functions to make calculations and analyze data.
• Date functions. You can use these functions to manipulate dates.
• Text functions. You can use these functions to join characters or lines, search for or extract a group of characters, or calculate the length of the text.