ParaView/Users Guide/Python Calculator

Introduction

The Python Calculator is a ParaView filter that processes one or more input arrays based on an expression provided by the user to produce a new output array. The parameters of the filter include the expression, the association of the output array (Point or Cell Data), the name of output array and a toggle that controls whether the input arrays are copied to the output. In this document, we introduce the use of the Python Calculator and provide a list of functions available to the user.

Note that the Python Calculator depends on Python and NumPy. All ParaView binaries distributed by Kitware are built with these to enable the calculator. If you have built ParaView yourself, you have to make sure that NumPy is installed and that PARAVIEW_ENABLE_PYTHON is turned on when configuring the ParaView build.

Basic Tutorial

Start by creating a Sphere source and applying the Python Calculator to it. As the first expression, use the following and apply:

<source lang="python"> 5 </source>

This should create an array name "result" in the output point data. Note that this is an array that has a value of 5 for each point. When the expression results in a single value, the calculator will automatically make an constant array. Next, try the following:

<source lang="python"> Normals </source>

Now the "result" array should be the same as the input array Normals. As described in detail later, various functions are available through the calculator. For example, the following is a valid expression.

<source lang="python"> sin(Normals) + 5 </source>

It is very important to note that the Python Calculator has to produce one value per point or cell depending on the Array Association parameter. Most of the functions described here apply individually to all point or cell values and produce an array as the same dimensions as the input. However, some of them (such as min() and max()) produce single values.

Basic Operations

- details about the expected output here - splitting arrays - merging arrays - constants - point to numpy documentation

Functions

- point the numpy documentation