def test_get_angle_cartesian_vec_input_validation():
get_angle_cartesian_vec(np.empty((2, 3)), np.empty((5, 3)))
def _generate_lookup_table(recip_latt,
reciprocal_radius: float,
unique: bool = True):
"""Generate a look-up table with all combinations of indices,
including their reciprocal distances and the angle between
them.
Parameters
----------
recip_latt : :class:`diffpy.structure.lattice.Lattice`
Reciprocal lattice
reciprocal_radius : float
The maximum g-vector magnitude to be included in the library.
unique : bool
Return a unique list of phase measurements
Returns
-------
indices : np.array
Nx2x3 numpy array containing the miller indices for
reflection1, reflection2
measurements : np.array
Nx3 numpy array containing len1, len2, angle
"""
miller_indices, coordinates, distances = get_points_in_sphere(
recip_latt, reciprocal_radius)
# Create pair_indices for selecting all point pair combinations
num_indices = len(miller_indices)
pair_a_indices, pair_b_indices = np.mgrid[:num_indices, :num_indices]
# Only select one of the permutations and don't pair an index with
# itself (select above diagonal)
upper_indices = np.triu_indices(num_indices, 1)
pair_a_indices = pair_a_indices[upper_indices].ravel()
pair_b_indices = pair_b_indices[upper_indices].ravel()
# Mask off origin (0, 0, 0)
origin_index = num_indices // 2
pair_a_indices = pair_a_indices[pair_a_indices != origin_index]
pair_b_indices = pair_b_indices[pair_b_indices != origin_index]
pair_indices = np.vstack([pair_a_indices, pair_b_indices])
# Create library entries
angles = get_angle_cartesian_vec(coordinates[pair_a_indices],
coordinates[pair_b_indices])
pair_distances = distances[pair_indices.T]
# Ensure longest vector is first
len_sort = np.fliplr(pair_distances.argsort(axis=1))
# phase_index_pairs is a list of [hkl1, hkl2]
phase_index_pairs = np.take_along_axis(miller_indices[pair_indices.T],
len_sort[:, :, np.newaxis],
axis=1)
# phase_measurements is a list of [len1, len2, angle]
phase_measurements = np.column_stack((np.take_along_axis(pair_distances,
len_sort,
axis=1), angles))
if unique:
# Only keep unique triplets
measurements, measurement_indices = np.unique(phase_measurements,
axis=0,
return_index=True)
indices = phase_index_pairs[measurement_indices]
else:
measurements = phase_measurements
indices = phase_index_pairs
return measurements, indices
def test_get_angle_cartesian_vec(a, b, expected_angles):
angles = get_angle_cartesian_vec(a, b)
np.testing.assert_allclose(angles, expected_angles)
def get_vector_library(self, reciprocal_radius):
"""Calculates a library of diffraction vectors and pairwise inter-vector
angles for a library of crystal structures.
Parameters
----------
reciprocal_radius : float
The maximum g-vector magnitude to be included in the library.
Returns
-------
vector_library : :class:`DiffractionVectorLibrary`
Mapping of phase identifier to phase information in dictionary
format.
"""
# Define DiffractionVectorLibrary object to contain results
vector_library = DiffractionVectorLibrary()
# Get structures from structure library
structure_library = self.structures.struct_lib
# Iterate through phases in library.
for phase_name in structure_library.keys():
# Get diffpy.structure object associated with phase
structure = structure_library[phase_name][0]
# Get reciprocal lattice points within reciprocal_radius
recip_latt = structure.lattice.reciprocal()
miller_indices, coordinates, distances = get_points_in_sphere(
recip_latt, reciprocal_radius)
# Create pair_indices for selecting all point pair combinations
num_indices = len(miller_indices)
pair_a_indices, pair_b_indices = np.mgrid[:num_indices, :
num_indices]
# Only select one of the permutations and don't pair an index with
# itself (select above diagonal)
upper_indices = np.triu_indices(num_indices, 1)
pair_a_indices = pair_a_indices[upper_indices].ravel()
pair_b_indices = pair_b_indices[upper_indices].ravel()
# Mask off origin (0, 0, 0)
origin_index = num_indices // 2
pair_a_indices = pair_a_indices[pair_a_indices != origin_index]
pair_b_indices = pair_b_indices[pair_b_indices != origin_index]
pair_indices = np.vstack([pair_a_indices, pair_b_indices])
# Create library entries
angles = get_angle_cartesian_vec(coordinates[pair_a_indices],
coordinates[pair_b_indices])
pair_distances = distances[pair_indices.T]
# Ensure longest vector is first
len_sort = np.fliplr(pair_distances.argsort(axis=1))
# phase_index_pairs is a list of [hkl1, hkl2]
phase_index_pairs = np.take_along_axis(
miller_indices[pair_indices.T],
len_sort[:, :, np.newaxis],
axis=1)
# phase_measurements is a list of [len1, len2, angle]
phase_measurements = np.column_stack(
(np.take_along_axis(pair_distances, len_sort, axis=1), angles))
# Only keep unique triplets
unique_measurements, unique_measurement_indices = np.unique(
phase_measurements, axis=0, return_index=True)
vector_library[phase_name] = {
'indices': phase_index_pairs[unique_measurement_indices],
'measurements': unique_measurements
}
# Pass attributes to diffraction library from structure library.
vector_library.identifiers = self.structures.identifiers
vector_library.structures = self.structures.structures
vector_library.reciprocal_radius = reciprocal_radius
return vector_library
