2.3.2.3 Substitution Notation

LabTalk-Substitution-Notation

Run-time substitution of LabTalk variables and variable expressions occurs routinely during Origin graphing and analysis operations. It also a cornerstone of any repetitive batch operation (import, analysis, graphing and graph export).

Substitution in Origin occurs in these four important places:

• LabTalk scripts
• Column and cell-formula expressions
• Text labels including graph axis titles, graph legends and text objects added to graphs, worksheets, etc.
• Labeling of data plots and points in graphs

When a script is executed, it is sent to the LabTalk interpreter. Among other tasks, the interpreter searches for special substitution notations, which are identified by their initial characters, % or $. When such substitution notation is found, the interpreter replaces the original string with another string. The value of the substituted string is unknown until the statement is actually executed. Thus, this procedure is called a run-time string substitution.

Types of Substitution

There are four types of run-time substitutions:

• String register substitution %A - %Z, etc.
• %( ) Substitution, a powerful notation to resolve %(str$), %(range), worksheet info and column dataset names, worksheet cells, legends, etc.
• $( ) Substitution, where $(expression) resolves the numeric expression and formats the result as a string.
• %n Macro and Script substitutions of the form %n, where arguments are passed to a macro or a script.