About CLEM

The Control Language for Expression Manipulation (CLEM) is a powerful language for analyzing and manipulating the data that flows along IBM® SPSS® Modeler streams. Data miners use CLEM extensively in stream operations to perform tasks as simple as deriving profit from cost and revenue data or as complex as transforming web log data into a set of fields and records with usable information.

CLEM is used within IBM SPSS Modeler to:

• Compare and evaluate conditions on record fields.
• Derive values for new fields.
• Derive new values for existing fields.
• Reason about the sequence of records.
• Insert data from records into reports.

CLEM expressions are indispensable for data preparation in IBM SPSS Modeler and can be used in a wide range of nodes—from record and field operations (Select, Balance, Filler) to plots and output (Analysis, Report, Table). For example, you can use CLEM in a Derive node to create a new field based on a formula such as ratio.

CLEM expressions can also be used for global search and replace operations. For example, the expression @NULL(@FIELD) can be used in a Filler node to replace system-missing values with the integer value 0. (To replace user-missing values, also called blanks, use the @BLANK function.)