def _cell_derivatives(narray, dataset, attribute_type, filter):
# basic error checking
if not dataset:
raise RuntimeError, 'Need a dataset to compute gradients'
if len(narray.shape) == 1:
narray = narray.reshape((narray.shape[0], 1))
if narray.shape[0] != dataset.GetNumberOfPoints():
raise RuntimeError, 'The number of points does not match the number of tuples in the array'
ncomp = narray.shape[1]
if attribute_type == 'scalars' and ncomp != 1:
raise RuntimeError, 'This function expects scalars.'
if attribute_type == 'vectors' and ncomp != 3:
raise RuntimeError, 'This function expects vectors.'
# create a dataset with only our array but the same geometry/topology
ds = dataset.NewInstance()
ds.CopyStructure(dataset.VTKObject)
# numpy_to_vtk converts only contiguous arrays
if not narray.flags.contiguous:
narray = narray.copy()
varray = numpy_support.numpy_to_vtk(narray)
if attribute_type == 'scalars':
varray.SetName('scalars')
ds.GetPointData().SetScalars(varray)
else:
varray.SetName('vectors')
ds.GetPointData().SetVectors(varray)
# setup and execute the pipeline
# filter (vtkCellDerivatives) must have all of its properties
# set
filter.SetInput(ds)
ds.UnRegister(None)
c2p = vtk.vtkCellDataToPointData()
c2p.SetInputConnection(filter.GetOutputPort())
c2p.Update()
return c2p.GetOutput().GetPointData()
def gradient(narray, dataset=None):
"Computes the gradient of a point-centered scalar array over a given dataset."
if not dataset:
dataset = narray.DataSet
if not dataset:
raise RuntimeError, 'Need a dataset to compute gradients'
if len(narray.shape) == 1:
narray = narray.reshape((narray.shape[0], 1))
if narray.shape[0] != narray.GetNumberOfTuples():
raise RuntimeError, 'The number of points does not match the number of tuples in the array'
if narray.shape[1] > 1:
raise RuntimeError, 'Gradient only works with 1 component arrays'
ds = dataset.NewInstance()
ds.CopyStructure(dataset.VTKObject)
# numpy_to_vtk converts only contiguous arrays
if not narray.flags.contiguous:
narray = narray.copy()
varray = numpy_support.numpy_to_vtk(narray)
varray.SetName('scalars')
ds.GetPointData().SetScalars(varray)
cd = vtk.vtkCellDerivatives()
cd.SetInput(ds)
ds.UnRegister(None)
c2p = vtk.vtkCellDataToPointData()
c2p.SetInputConnection(cd.GetOutputPort())
c2p.Update()
retVal = c2p.GetOutput().GetPointData().GetVectors()
try:
if narray.GetName():
retVal.SetName("gradient of " + narray.GetName())
else:
retVal.SetName("gradient")
except AttributeError:
retVal.SetName("gradient")
return dataset_adapter.vtkDataArrayToVTKArray(retVal, dataset)
def _cell_derivatives (narray, dataset, attribute_type, filter):
if not dataset :
raise RuntimeError, 'Need a dataset to compute _cell_derivatives.'
# Reshape n dimensional vector to n by 1 matrix
if len(narray.shape) == 1 :
narray = narray.reshape((narray.shape[0], 1))
ncomp = narray.shape[1]
if attribute_type == 'scalars' and ncomp != 1 :
raise RuntimeError, 'This function expects scalars.'\
'Input shape ' + narray.shape
if attribute_type == 'vectors' and ncomp != 3 :
raise RuntimeError, 'This function expects vectors.'\
'Input shape ' + narray.shape
# numpy_to_vtk converts only contiguous arrays
if not narray.flags.contiguous : narray = narray.copy()
varray = numpy_support.numpy_to_vtk(narray)
if attribute_type == 'scalars': varray.SetName('scalars')
else : varray.SetName('vectors')
# create a dataset with only our array but the same geometry/topology
ds = dataset.NewInstance()
ds.UnRegister(None)
ds.CopyStructure(dataset.VTKObject)
if dataset_adapter.ArrayAssociation.FIELD == narray.Association :
raise RuntimeError, 'Unknown data association. Data should be associated with points or cells.'
if dataset_adapter.ArrayAssociation.POINT == narray.Association :
# Work on point data
if narray.shape[0] != dataset.GetNumberOfPoints() :
raise RuntimeError, 'The number of points does not match the number of tuples in the array'
if attribute_type == 'scalars': ds.GetPointData().SetScalars(varray)
else : ds.GetPointData().SetVectors(varray)
elif dataset_adapter.ArrayAssociation.CELL == narray.Association :
# Work on cell data
if narray.shape[0] != dataset.GetNumberOfCells() :
raise RuntimeError, 'The number of does not match the number of tuples in the array'
# Since vtkCellDerivatives only works with point data, we need to convert
# the cell data to point data first.
ds2 = dataset.NewInstance()
ds2.UnRegister(None)
ds2.CopyStructure(dataset.VTKObject)
if attribute_type == 'scalars' : ds2.GetCellData().SetScalars(varray)
else : ds2.GetCellData().SetVectors(varray)
c2p = vtk.vtkCellDataToPointData()
c2p.SetInputData(ds2)
c2p.Update()
# Set the output to the ds dataset
if attribute_type == 'scalars':
ds.GetPointData().SetScalars(c2p.GetOutput().GetPointData().GetScalars())
else:
ds.GetPointData().SetVectors(c2p.GetOutput().GetPointData().GetVectors())
filter.SetInputData(ds)
if dataset_adapter.ArrayAssociation.POINT == narray.Association :
# Since the data is associated with cell and the query is on points
# we have to convert to point data before returning
c2p = vtk.vtkCellDataToPointData()
c2p.SetInputConnection(filter.GetOutputPort())
c2p.Update()
return c2p.GetOutput().GetPointData()
elif dataset_adapter.ArrayAssociation.CELL == narray.Association :
filter.Update()
return filter.GetOutput().GetCellData()
else :
# We shall never reach here
raise RuntimeError, 'Unknown data association. Data should be associated with points or cells.'