6.7 KiB
6.7 KiB
网格删除
以下保留原笔记本的代码和已保存输出；转换过程中未重新执行代码。
本教程演示球面坐标下的网格删除操作。首先导入所需的库。
import meshkernel
import matplotlib.pyplot as plt
import numpy as np
from pathlib import Path
import datetime as dt
删除简单网格
创建矩形网格。
lon_min, lon_max = -2.5, -1.3
lat_min, lat_max = 48.4, 49.0
lon_res, lat_res = 0.01, 0.01
make_grid_parameters = meshkernel.MakeGridParameters()
make_grid_parameters.origin_x = lon_min
make_grid_parameters.origin_y = lat_min
make_grid_parameters.upper_right_x = lon_max
make_grid_parameters.upper_right_y = lat_max
make_grid_parameters.block_size_x = lon_res
make_grid_parameters.block_size_y = lat_res
mk2 = meshkernel.MeshKernel(projection=meshkernel.ProjectionType.SPHERICAL)
mk2.get_projection()
mk2.curvilinear_compute_rectangular_grid_on_extension(make_grid_parameters)
mk2.curvilinear_convert_to_mesh2d()
mesh2d_orig = mk2.mesh2d_get()
创建用于删除操作的多边形。
pol_x = np.array(
[
-2.554972,
-2.475056,
-2.488361,
-2.4375,
-2.418417,
-2.319139,
-2.313333,
-2.28625,
-2.336694,
-2.314167,
-2.246722,
-2.213361,
-2.195028,
-2.182472,
-2.157944,
-2.175444,
-2.152528,
-2.125889,
-2.152528,
-2.04925,
-2.057944,
-2.032111,
-2.034639,
-1.997083,
-2.015472,
-1.975028,
-1.962972,
-1.989667,
-1.957139,
-2.015056,
-2.004583,
-2.033,
-1.98925,
-1.992556,
-1.941667,
-1.962972,
-1.935056,
-1.905028,
-1.843389,
-1.837111,
-1.872111,
-1.842528,
-1.771667,
-1.635028,
-1.592528,
-1.511722,
-1.51,
-1.470056,
-1.43,
-1.3575,
-1.412889,
-1.389222,
-1.447583,
-1.453361,
-1.505028,
-1.530056,
-1.570444,
-1.576278,
-1.615444,
-1.580417,
-1.2,
-1.2,
-2.6,
-2.554972,
]
)
pol_y = np.array(
[
48.599583,
48.622889,
48.64625,
48.653722,
48.634556,
48.690389,
48.672083,
48.667444,
48.620389,
48.612111,
48.645444,
48.57375,
48.611222,
48.577889,
48.587472,
48.597472,
48.618722,
48.604528,
48.633694,
48.639583,
48.625833,
48.624972,
48.604944,
48.578306,
48.571667,
48.536222,
48.549944,
48.583333,
48.578306,
48.598722,
48.614111,
48.650806,
48.668722,
48.684583,
48.684583,
48.689972,
48.702917,
48.690417,
48.712083,
48.679972,
48.645806,
48.616222,
48.603722,
48.617889,
48.639611,
48.621222,
48.632056,
48.625417,
48.643722,
48.63375,
48.659139,
48.67625,
48.655389,
48.672083,
48.687056,
48.73125,
48.744167,
48.821639,
48.835806,
48.856639,
48.9,
48.3,
48.3,
48.599583,
]
)
执行网格删除。由于网格较大，可能需要约一分钟。
delete_pol_geom = meshkernel.GeometryList(x_coordinates=pol_x, y_coordinates=pol_y)
print("Deleting grid with coastlines: ", end="")
dtstart = dt.datetime.now()
mk2.mesh2d_delete(
geometry_list=delete_pol_geom,
delete_option=meshkernel.DeleteMeshOption.INSIDE_NOT_INTERSECTED,
invert_deletion=False,
)
print(f"{(dt.datetime.now()-dtstart).total_seconds():.2f} sec")
Deleting grid with coastlines: 0.02 sec
绘制删除后的结果。
plt.close("all")
figsize = (8, 4)
mesh2d = mk2.mesh2d_get()
fig, ax = plt.subplots(figsize=figsize)
mesh2d_orig.plot_edges(ax, color="grey")
mesh2d.plot_edges(ax, color="k")
ax.plot(pol_x, pol_y, "r", linewidth=1)
ax.set_ylim(lat_min - 0.11, lat_max)
(48.29, 49.0)
使用全球多边形删除网格
创建矩形网格。
lon_min, lon_max = -6, 2
lat_min, lat_max = 48.5, 51.2
lon_res, lat_res = 0.2, 0.2
make_grid_parameters = meshkernel.MakeGridParameters()
make_grid_parameters.origin_x = lon_min
make_grid_parameters.origin_y = lat_min
make_grid_parameters.upper_right_x = lon_max
make_grid_parameters.upper_right_y = lat_max
make_grid_parameters.block_size_x = lon_res
make_grid_parameters.block_size_y = lat_res
mk = meshkernel.MeshKernel(projection=meshkernel.ProjectionType.SPHERICAL)
mk.curvilinear_compute_rectangular_grid_on_extension(make_grid_parameters)
mk.curvilinear_convert_to_mesh2d()
mesh2d = mk.mesh2d_get()
mesh2d_orig = mk.mesh2d_get()
num_faces_before = len(mesh2d.face_x)
num_columns = int((lat_max - lat_min) / 0.2)
num_rows = int((lon_max - lon_min) / 0.2)
print("num_faces_before ", num_faces_before)
print("num_columns ", num_columns)
print("num_rows ", num_rows)
num_faces_before 1120
num_columns 13
num_rows 40
导入全球海岸线，约包含 130,000 条线段。
polygon_file_path = Path().absolute() / "data_examples" / "global_coastline.pol"
polygon_np = np.loadtxt(polygon_file_path, comments="*", skiprows=2, dtype=np.double)
pol_x = np.array(polygon_np[:, 0], dtype=np.double)
pol_y = np.array(polygon_np[:, 1], dtype=np.double)
print(">> deleting grid with coastlines: ", end="")
dtstart = dt.datetime.now()
delete_pol_geom = meshkernel.GeometryList(x_coordinates=pol_x, y_coordinates=pol_y)
mk.mesh2d_delete(
geometry_list=delete_pol_geom,
delete_option=meshkernel.DeleteMeshOption.INSIDE_NOT_INTERSECTED,
invert_deletion=False,
)
print(f"{(dt.datetime.now()-dtstart).total_seconds():.2f} sec")
>> deleting grid with coastlines: 1.36 sec
plt.close("all")
figsize = (8, 4)
mesh2d = mk.mesh2d_get()
fig, ax = plt.subplots(figsize=figsize)
mesh2d_orig.plot_edges(ax, color="grey")
mesh2d.plot_edges(ax, color="k")
ax.plot(pol_x, pol_y, "r", linewidth=1)
ax.set_xlim(lon_min, lon_max)
ax.set_ylim(lat_min, lat_max)
num_faces_after = len(mesh2d.face_x)
print("num_faces_after ", num_faces_before)
print("deleted faces ", num_faces_before - num_faces_after)
num_faces_after 1120
deleted faces 213
