VTK

The vtk module contains classes to allow I/O of meshes and fields using the VTK Legacy Format. Note that this currently only supports scalar or 2D/3D vector (column matrix) fields that live on the vertices ( shape [1,0,0]). Support for tensorial fields and fields on cells coming soon.

VTKExporter

This class can be used to export the field(s) and/or a mesh at a given state to a single .vtk file. To use it, import the vtk module:

import vtk

Initialize the VTKExporter

var vtkE = VTKExporter(obj)

where obj can either be

• A Mesh object: This prepares the Mesh for exporting.
• A Field object: This prepares both the Field and the Mesh associated with it for exporting.

Use the export method to export to a VTK file.

vtkE.export("output.vtk")

Optionally, use the addfield method to add one or more fields before exporting:

vtkE.addfield(f, fieldname="f")

where,

• f is the field object to be exported
• fieldname is an optional argument that assigns a name to the field in the VTK file. This name is required to be a character string without embedded whitespace. If not provided, the name would be either "scalars" or "vectors" depending on the field type**.

** Note that this currently only supports scalar or 2D/3D vector (column matrix) fields that live on the vertices ( shape [1,0,0]). Support for tensorial fields and fields on cells coming soon.

Minimal example:

import vtk
import meshtools

var m1 = LineMesh(fn (t) [t,0,0], -1..1:2)

var vtkE = VTKExporter(m1) // Export just the mesh 

vtkE.export("mesh.vtk")

var f1 = Field(m1, fn(x,y,z) x)

var g1 = Field(m1, fn(x,y,z) Matrix([x,2*x,3*x]))

vtkE = VTKExporter(f1, fieldname="f") // Export fields

vtkE.addfield(g1, fieldname="g")

vtkE.export("data.vtk")

VTKImporter

This class can be used to import the field(s) and/or the mesh at a given state from a single .vtk file. To use it, import the vtk module:

import vtk

Initialize the VTKImporter with the filename

var vtkI = VTKImporter("output.vtk")

Use the mesh method to get the mesh:

var mesh = vtkI.mesh()

Use the field method to get the field:

var f = vtkI.field(fieldname)

Use the fieldlist method to get the list of the names of the fields contained in the file:

print vtkI.fieldlist()

Use the containsfield method to check whether the file contains a field by a given fieldname:

if (tkI.containsfield(fieldname)) {
    ... 
}

where fieldname is the name assigned to the field in the .vtk file

Minimal example:

import vtk
import meshtools 

var vtkI = VTKImporter("data.vtk")

var m = vtkI.mesh()

var f = vtkI.field("f")

var g = vtkI.field("g")