ParaView Expression Manager

ParaView provides many different filters to process dataset attributes. Some treatments, such as isocontouring, stream tracing and histogram computing, effectively perform a predefined set of mathematical operations.

The Calculator and Python Calculator tools enable one to customize the data processing through a user-defined single line expression. Up until now, writing this expression was a manual act that had to be repeated at every filter creation even if one would like to just re-use a common operation.

Enter The Expression Manager! Included in the ParaView 5.11 release among many nice features (see the release notes) this new interface element allows users to easily store expressions and access them quickly when they are most needed. Each expression can be named, to help future reuse, and has an associated group so it is easy to filter Python expressions from others.

Integrated in your workflow

From the Property Panel, the one-line property text entry is augmented with:

• a drop down list to access existing expressions
• a “Save Current Expression” button
• a shortcut to the Choose Expression dialog

High level configuration

The Choose Expression dialog, also accessible from the Tools -> Manage Expressions menu item, is an editable and searchable list of your stored expressions. In order to facilitate expression usage, they are included in the properties panel menu and labeled by their given names. Two types of “one-liners” are supported:

• Expression: mathematical operation intended to be used in the Calculator filter.
• Python: one-line python code, intended to be used in some python filters, such as PythonCalculator and PythonAnnotation

When opening the Expression Dialog from a filter, it is possible to set the expression property with the currently selected line by clicking on Use Current.

ParaView keeps track of the expressions through the settings, but they can also be exported to a JSON file for backup and sharing.

Acknowledgements

This work was founded by CEA, DAM, DIF, F-91297 Arpajon, France