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Copy pathpythonmesh.py
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131 lines (122 loc) · 4.28 KB
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def parse_gmsh_file(file):
sections = set(["$MeshFormat", "$PhysicalNames", "$Nodes", "$Elements"])
lineno = 0
section_count = 0
section_expected = 0
dimension = 0
with open(file, "r") as ih:
state = "begin"
for line in ih:
line = line.rstrip()
lineno += 1
if state == "begin":
if line in sections:
state = line
else:
raise RuntimeError("Error Line %d" % lineno)
elif line.find("$End") == 0:
state = "begin"
section_count = 0
section_expected = None
elif state == "$MeshFormat":
continue
elif state == "$PhysicalNames":
if not section_expected:
section_expected = int(line)
physical_names = []
else:
line = line.split()
name = line[2][1:-1]
physical_names.append((name, int(line[0]), int(line[1])))
section_count += 1
elif state == "$Nodes":
if not section_expected:
section_expected = int(line)
nodes = []
else:
line = line.split()
nodes.append(
[int(line[0]), float(line[1]), float(line[2]), float(line[3])]
)
section_count += 1
elif state == "$Elements":
if not section_expected:
section_expected = int(line)
elements = [None] * section_expected
else:
elements[section_count] = [int(x) for x in line.split()]
section_count += 1
else:
raise RuntimeError("Unknown %s" % line)
dimension = max([x[1] for x in physical_names])
return {
"dimension": dimension,
"physical_names": physical_names,
"coordinates": nodes,
"elements": elements,
}
def read_gmsh_file(filename):
"""reads gmsh file and converts to python representation"""
data = parse_gmsh_file(filename)
# namemap = {}
print("%d dimension" % data["dimension"])
print("%d coordinates" % len(data["coordinates"]))
# for i in sorted(data['physical_names'].keys()):
# print "%s %s %d" % (i, data['physical_names'][i], len(data['elements'][i]))
# namemap[data['physical_names'][i]] = i
coordinate_indexes = [x[0] for x in data["coordinates"]]
max_coordinate_index = max(coordinate_indexes)
coordinate_to_index = [-1] * (max_coordinate_index + 1)
for i, j in enumerate(coordinate_indexes):
coordinate_to_index[j] = i
coordinates = []
for i in data["coordinates"]:
coordinates.extend(i[1:])
_all_physical_numbers = sorted(set([x[3] for x in data["elements"]]))
sorted_physical_names = sorted(data["physical_names"], key=lambda x: x[0])
physical_number_map = {
1: {},
2: {},
3: {},
}
for i, j in enumerate(sorted_physical_names):
# mapped dimension, physical number, new index
physical_number_map[j[1]][j[2]] = i
physical_names = [x[0] for x in sorted_physical_names]
# gmsh format
# elm-number elm-type number-of-tags < tag > ... node-number-list
# our format
elements = []
for i in data["elements"]:
t = i[1]
if t == 4:
# tetrahedron
etype = 3
dimension = 3
elif t == 2:
# triangle
etype = 2
dimension = 2
elif t == 1:
# edge
etype = 1
dimension = 1
elif t == 15:
# point
etype = 0
else:
raise RuntimeError("Cannot handle element type " % i)
# physical number
# will be remapped later
pnum = physical_number_map[dimension][i[3]]
# nodes
# position 2 + number of tags
nodes = i[i[2] + 3 :]
nodes = [coordinate_to_index[x] for x in nodes]
elements.extend([etype, pnum])
elements.extend(nodes)
return {
"physical_names": physical_names,
"coordinates": coordinates,
"elements": elements,
}