Documentation for vtkxml-builder

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vtkxml

This module provides tools for creating VTK XML files for use with ParaView and other similar data visualization tools. It is meant to be used within a separate post-processing script to turn raw data output into an XML file.

Todo

Add writer for other grid types

class vtkxml.VtuWriter(bit64=False)

Parameters:bit64 – If true, use 64 bit value strings.

Writer for VTK unstructured grid XML files. The primary public methods are write_data_file() and write_pvd_file().

Usage example:

>>> import tempfile, os
>>> td = tempfile.gettempdir()
>>> w= VtuWriter()
>>> v = {'positions': [[1, 2.5, 3], [2, 1, 3], [3.5, 1, 2]]}
>>> s = {'temps': [1.0, 2.0, 1.5]}
>>> w.write_data_file(os.path.join(td, 'vtu0.vtu'), s, v)

Todo

Add support for cell and vert data in addition to point data

generate_scalar(doc, name, data, datatype)

Parameters:

• doc – An xml.dom.minidom.Document object.
• name – Name of the data series.
• data – List of data series values.
• datatype – Data type to use for data series.

Generates a <DataArray> XML element that contains scalar data.

generate_vector(doc, name, data, datatype)

Parameters:

• doc – An xml.dom.minidom.Document object.
• name – Name of the data series.
• data – List of data series values.
• datatype – Data type to use for data series.

Generates a <DataArray> XML element that contains vector data.

guess_scalar_type(data)

Parameters:data – A list of scalar data values.

Guess the data type of the series. Assumes 32 bit values unless bit64 was specified to the constructor. If a valid type cannot be found, a ValueError exception is raised.

>>> w32 = VtuWriter()
>>> w32.guess_scalar_type([1,2,3])
'UInt32'
>>> w32.guess_scalar_type([-1,2,3])
'Int32'
>>> w32.guess_scalar_type([1.0, 2.0, 3.0])
'Float32'
>>> w32.guess_scalar_type([1.0, 2, 3.0])
'Float32'
>>> w64 = VtuWriter(bit64=True)
>>> w64.guess_scalar_type([1,2,3])
'UInt64'
>>> w64.guess_scalar_type([-1,2,3])
'Int64'
>>> w64.guess_scalar_type([1.0, 2.0, 3.0])
'Float64'
>>> w64.guess_scalar_type([1.0, 2, 3.0])
'Float64'

guess_vector_type(data)

Parameters:data – A list of vector element lists. Each list contains the data for a particular element of a vector.

Guess the data type of the vector series. Behaves the same as guess_scalar_type.

>>> w32 = VtuWriter()
>>> w32.guess_vector_type([[1,2,3], [1,2,3]])
'UInt32'
>>> w32.guess_vector_type([[-1,2,3], [1,2,3]])
'Int32'
>>> w32.guess_vector_type([[1.0, 2.0, 3.0], [1.0, 2.0, 3.0]])
'Float32'
>>> w32.guess_vector_type([[1.0, 2, 3.0], [1, 2, 3]])
'Float32'
>>> w64 = VtuWriter(bit64=True)
>>> w64.guess_vector_type([[1,2,3], [1,2,3]])
'UInt64'
>>> w64.guess_vector_type([[-1,2,3], [1,2,3]])
'Int64'
>>> w64.guess_vector_type([[1.0, 2.0, 3.0], [1.0, 2.0, 3.0]])
'Float64'
>>> w64.guess_vector_type([[1.0, 2, 3.0], [1, 2, 3]])
'Float64'

static vectors_to_string(*vectors)

Parameters:*vectors – A list of lists, each with an element of a vector.

Convert a list of one or more vectors into a string, where each line contains one element from each of the vectors. See the example below. Note that the order of the elements is preserved.

>>> print VtuWriter.vectors_to_string([1,2,3], [4,5,6])
1 4
2 5
3 6
>>> print VtuWriter.vectors_to_string([1,2,3])
1
2
3

write_data_file(fn, scalars, vectors, types={}, pname='positions')

Parameters:

• fn – Filename to save XML document to, including extension.
• scalars – Dictionary of scalar data series.
• vectors – Dictionary of vector data series.
• types – Dictionary of type strings.
• pname – Positions vector series name.

Create an XML file with filename fn that contains the data given. Data are passed in using the scalars and vectors parameters. These are dictionaries of the form

{<field_name>: [<elements_1>, <elements_2>,...,<elements_n>], ...}

for vectors and

{<field_name>: <elements>, ...}

for scalars, where <elements> and <elements_i> are lists of data values. So, for example, a bunch of particle positions might be passed in using a vectors dictionary such as

{'positions': [[1,2,3], [1,2,3], [1,2,3]]}

which would correspond to particles located at (1, 1, 1), (2, 2, 2), (3, 3, 3). Similarly, two scalar variables could be created using a scalars argument like the one given below.

{'radius': [3, 2, 5], 'mass': [5, 8, 3]}

In this case, the particle located at (1, 1, 1) in the vectors example would have radius 3 and mass 5, etc.

Data types may optionally be provided for each data series using the types parameter. Vector and scalars types are provided in a single dictionary in which the keys are the field names from the vector and scalar arguments and the values are valid VTK data type strings such as UInt32 or Float32. Any data series that do not have types provided will have their types auto-detected.

Finally, the pname parameter may be used to specify the name of a vector data series that should be treated as points in the unstructured grid. The default is positions. A points vector is required.

write_pvd_file(fn)

Parameters:fn – Filename to save PVD file to.

Write a PVD file with filename fn that contains references to the data files previously created with this instance.

Todo List

Todo

Add writer for other grid types

(The original entry is located in /var/build/user_builds/vtkxml-builder/checkouts/latest/vtkxml/vtkxml.py:docstring of vtkxml, line 8.)

Todo

Add support for cell and vert data in addition to point data

(The original entry is located in /var/build/user_builds/vtkxml-builder/checkouts/latest/vtkxml/vtkxml.py:docstring of vtkxml.VtuWriter, line 15.)

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