# Copyright (C) 2021 - 2024 ANSYS, Inc. and/or its affiliates.
# SPDX-License-Identifier: MIT
#
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import typing
import numpy as np
import pandas as pd
from ansys.dyna.core import Deck
[docs]
def get_nid_to_index_mapping(nodes) -> typing.Dict:
"""Given a node id, output the node index as a dict"""
mapping = {}
for idx, node in nodes.iterrows():
mapping[node["nid"]] = idx
return mapping
[docs]
def merge_keywords(
deck: Deck,
) -> typing.Tuple[pd.DataFrame, typing.Dict]:
"""
Merge mesh keywords.
Given a deck, merges specific keywords (NODE, ELEMENT_SHELL, ELEMENT_BEAM, ELEMENT_SOLID)
and returns tham as data frames.
"""
nodes_temp = [kwd.nodes for kwd in deck.get_kwds_by_type("NODE")]
nodes = pd.concat(nodes_temp) if len(nodes_temp) else pd.DataFrame()
df_list = {}
for item in ["SHELL", "BEAM", "SOLID"]:
matching_elements = [kwd.elements for kwd in deck.get_kwds_by_type("ELEMENT") if kwd.subkeyword == item]
df_list[item] = pd.concat(matching_elements) if len(matching_elements) else pd.DataFrame()
return (
nodes,
df_list,
) # solids
[docs]
def process_nodes(nodes_df):
nodes_xyz = nodes_df[["x", "y", "z"]]
return nodes_xyz.to_numpy()
[docs]
def shell_facet_array(facets: pd.DataFrame) -> np.array:
"""
Get the shell facet array from the DataFrame.
Facets are a pandas frame that is a sequence of integers
or NAs with max length of 8.
valid rows contain 3,4,6, or 8 items consecutive from the
left. we don't plot quadratic edges so 6/8 collapse to 3/4
invalid rows are ignored, meaning they return an empty array
return an array of length 4 or 5 using the pyvista spec
for facets which includes a length prefix
[1,2,3]=>[3,1,2,3]
[1,2,3,0]=>[3,1,2,3]
[1,2,3,NA]=>[3,1,2,3]
"""
facet_array = np.empty(5, dtype=np.int32)
for idx, item in enumerate(facets):
# find the first empty column
if pd.isna(item) or item == 0:
if idx == 3 or idx == 6:
facet_array[0] = 3
return facet_array[:-1]
elif idx == 4:
facet_array[0] = 4
return facet_array
else:
# invalid
return np.empty(0)
# fill the output to the right of the prefix
if idx < 4:
facet_array[idx + 1] = item
facet_array[0] = 4
return facet_array
[docs]
def solid_array(solids: pd.DataFrame):
"""
Get the solid array from the DataFrame.
Solids are a pandas frame that is a sequence of integers
or NAs with max length of 28.
valid rows contain 3, 4, 6, or 8 items consecutive from the
left. We don't plot quadratic edges so 6/8 collapse to 3/4
invalid rows are ignored, meaning they return an empty array
return an array of length 4 or 5 using the pyvista spec
for facets which includes a length prefix
[1,2,3]=>[3,1,2,3]
[1,2,3,0]=>[3,1,2,3]
[1,2,3,NA]=>[3,1,2,3]
"""
# FACES CREATED BY THE SOLIDS BASED ON MANUAL
# A DUMMY ZERO IS PUT AS A PLACEHOLDER FOR THE LEN PREFIX
four_node_faces = [[0, 1, 2, 3], [0, 1, 2, 4], [0, 1, 3, 4], [0, 2, 3, 4]]
six_node_faces = [
[0, 1, 2, 5],
[0, 3, 4, 6],
[0, 2, 3, 5, 6],
[0, 1, 5, 6, 4],
[0, 1, 2, 3, 4],
]
eight_node_faces = [
[0, 1, 2, 3, 4],
[0, 1, 2, 5, 6],
[0, 5, 6, 7, 8],
[0, 3, 4, 7, 8],
[0, 2, 3, 6, 7],
[0, 1, 4, 5, 8],
]
facet_array = []
for idx, item in enumerate(solids):
# find the first empty column
if pd.isna(item) or item == 0:
if idx == 4:
facet_array = [len(facet) - 1 if i == 0 else solids[i - 1] for facet in four_node_faces for i in facet]
return facet_array
elif idx == 6:
facet_array = [len(facet) - 1 if i == 0 else solids[i - 1] for facet in six_node_faces for i in facet]
return facet_array
elif idx == 8:
facet_array = [len(facet) - 1 if i == 0 else solids[i - 1] for facet in eight_node_faces for i in facet]
return facet_array
else:
# invalid
return []
# fill the output to the right of the prefix
return np.array(facet_array)
[docs]
def line_array(lines: pd.DataFrame) -> np.array:
"""
Convert DataFrame to lines array.
`lines` is a pandas frame that is a sequence of integers
or NAs with max length of 2.
valid rows contain 2 items consecutive from the
left.
invalid rows are ignored, meaning they return an empty array
return an array of length 3 using the pyvista spec
for facets which includes a length prefix
[1,2,]=>[2,1,2]
[1,2,3,0]=>[]
[1,2,3,NA]=>[]
"""
line_array = np.empty(3, dtype=np.int32)
for idx, item in enumerate(lines):
# find the first empty column
if pd.isna(item) or item == 0:
if idx == 0 or idx == 1:
return np.empty(0)
# fill the output to the right of the prefix
if idx < 2:
line_array[idx + 1] = item
line_array[0] = 2
return line_array
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def map_facet_nid_to_index(flat_facets: np.array, mapping: typing.Dict) -> np.array:
"""Convert mapping to numpy array.
Given a flat list of facets or lines, use the mapping from nid to python index
to output the numbering system for pyvista from the numbering from dyna
"""
# Map the indexes but skip the prefix
flat_facets_indexed = np.empty(len(flat_facets), dtype=np.int32)
skip_flag = 0
for idx, item in np.ndenumerate(flat_facets):
if skip_flag == 0:
flat_facets_indexed[idx] = item
skip_flag -= int(item)
else:
flat_facets_indexed[idx] = mapping[item]
skip_flag += 1
return flat_facets_indexed
[docs]
def get_pyvista():
try:
import pyvista as pv
except ImportError:
raise Exception("plot is only supported if pyvista is installed")
return pv
[docs]
def get_polydata(deck: Deck, cwd=None):
"""Create the PolyData Object for plotting from a given deck with nodes and elements."""
# import this lazily (otherwise this adds over a second to the import time of pyDyna)
pv = get_pyvista()
# check kwargs for cwd. future more arguments to plot
flat_deck = deck.expand(cwd)
nodes_df, element_dict = merge_keywords(flat_deck)
shells_df = element_dict["SHELL"]
beams_df = element_dict["BEAM"]
solids_df = element_dict["SOLID"]
nodes_list = process_nodes(nodes_df)
if len(nodes_df) == 0 or len(shells_df) + len(beams_df) + len(solids_df) == 0:
raise Exception("missing node or element keyword to plot")
mapping = get_nid_to_index_mapping(nodes_df)
facets = extract_shell_facets(shells_df, mapping)
lines = extract_lines(beams_df, mapping)
solids = extract_solids(solids_df, mapping)
plot_data = pv.PolyData(nodes_list, [*facets, *solids])
if len(lines) > 0:
plot_data.lines = lines
return plot_data
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def plot_deck(deck, **args):
"""Plot the deck."""
plot_data = get_polydata(deck, args.pop("cwd", ""))
return plot_data.plot()
