Expressions are used to create new columns, but are just as powerful when applied to axes. They are recalculated on the fly in response to changes in the analysis, and by axis binding they can be used set an axis dynamically in response to marking. Expressions may involve one or more columns, aggregation measures, or mathematical expressions.
Overview
Custom expressions provide calculation logic. A single expression
language is used in two different settings:
- Column Expressions
Custom expressions can be used to define calculations creating
new columns. These expressions are referred to as Column Expressions.
The resulting column is considered static, since it is calculated
once and then added to a data table.
-
Axis Expressions
Expressions may define calculations used in the axes of visualizations. They are often referred to as dynamic, since the expressions are recalculated based on changes to the analysis.
Refer to the TIBCO Spotfire User's Guide for
details, especially the following topics: