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#!/usr/bin/env python3
# Use the proper idiom in the main module ...
# NOTE: See https://docs.python.org/3.12/library/multiprocessing.html#the-spawn-and-forkserver-start-methods
if __name__ == "__main__":
# Import standard modules ...
import os
# Import special modules ...
try:
import cartopy
cartopy.config.update(
{
"cache_dir" : os.path.expanduser("~/.local/share/cartopy_cache"),
}
)
except:
raise Exception("\"cartopy\" is not installed; run \"pip install --user Cartopy\"") from None
try:
import matplotlib
matplotlib.rcParams.update(
{
"backend" : "Agg", # NOTE: See https://matplotlib.org/stable/gallery/user_interfaces/canvasagg.html
"figure.dpi" : 300,
"figure.figsize" : (9.6, 7.2), # NOTE: See https://github.com/Guymer/misc/blob/main/README.md#matplotlib-figure-sizes
"font.size" : 8,
}
)
import matplotlib.pyplot
except:
raise Exception("\"matplotlib\" is not installed; run \"pip install --user matplotlib\"") from None
try:
import shapely
import shapely.geometry
import shapely.ops
except:
raise Exception("\"shapely\" is not installed; run \"pip install --user Shapely\"") from None
# Import my modules ...
try:
import pyguymer3
import pyguymer3.geo
import pyguymer3.image
except:
raise Exception("\"pyguymer3\" is not installed; you need to have the Python module from https://github.com/Guymer/PyGuymer3 located somewhere in your $PYTHONPATH") from None
# **************************************************************************
# List countries to find the antipodes of ...
# NOTE: Ignore Antarctica.
avoids = [
"United Kingdom",
"Akrotiri",
"Anguilla",
"Bermuda",
"Br. Indian Ocean Ter.",
"British Virgin Is.",
"Cayman Is.",
"Dhekelia",
"Falkland Is.",
"Gibraltar",
"Montserrat",
"Pitcairn Is.",
"S. Geo. and the Is.",
"Saint Helena",
"Turks and Caicos Is.",
"United States of America",
"American Samoa",
"Guam",
"Marshall Is.",
"Micronesia",
"N. Mariana Is.",
"Palau",
"Puerto Rico",
"U.S. Minor Outlying Is.",
"U.S. Virgin Is.",
"USNB Guantanamo Bay",
]
# Create colours and define number of angles and resolution ...
colours = ["red", "green", "blue", "cyan", "magenta", "yellow", "red"]
fill = 0.1 # [°]
nang = 361 # [#]
res = "10m"
simp = 0.01 # [°]
tol = 1.0e-10 # [°]
# Find file containing all the country shapes ...
sfile = cartopy.io.shapereader.natural_earth(
category = "cultural",
name = "admin_0_countries",
resolution = res,
)
# **************************************************************************
# * CREATE MULTIPOLYGON TO FIND THE BUFFER OF *
# **************************************************************************
# Create empty list ...
geoms = []
# Loop over records ...
for record in cartopy.io.shapereader.Reader(sfile).records():
# Create short-hand ...
neName = pyguymer3.geo.getRecordAttribute(record, "NAME")
# Check if this record is to be avoided ...
skip = True
if neName in avoids:
skip = False
# Skip this record if it is not a country to be avoided ...
if skip:
continue
# Add Polygons to the list ...
geoms += pyguymer3.geo.extract_polys(record.geometry)
# Convert list of Polygons to (unified) [Multi]Polygon ...
geoms = shapely.ops.unary_union(geoms).simplify(tol)
pyguymer3.geo.check(geoms)
# **************************************************************************
# Create figure ...
fg = matplotlib.pyplot.figure(figsize = (12.8, 7.2))
# Create axis ...
ax = pyguymer3.geo.add_axis(fg)
# Configure axis ...
pyguymer3.geo.add_map_background(ax, resolution = "large8192px")
# Add country outlines ...
for record in cartopy.io.shapereader.Reader(sfile).records():
ax.add_geometries(
pyguymer3.geo.extract_polys(record.geometry),
cartopy.crs.PlateCarree(),
edgecolor = "black",
facecolor = "none",
linewidth = 0.5,
)
# Initialize distance, labels and lines ...
dist2 = 0.0 # [km]
labels = []
lines = []
# Loop over distances ...
for i in range(7):
# Set distance ...
if i >= 6:
dist1 = 0.5e6 # [m]
else:
dist1 = 1.0e6 # [m]
dist2 += 0.001 * dist1 # [km]
# Find out how complicated the [Multi]Polygon is ...
npoints = 0 # [#]
npolys = 0 # [#]
for poly in pyguymer3.geo.extract_polys(geoms):
npoints += len(poly.exterior.coords) # [#]
npolys += 1 # [#]
for interior in poly.interiors:
npoints += len(interior.coords) # [#]
print(f"Calculating for {dist2:6,.0f} km (using {npoints:,d} points in {npolys:,d} Polygons) ...")
# Buffer area ...
# NOTE: geoms is the [Multi]Polygon to be buffered.
geoms = pyguymer3.geo.buffer(
geoms,
dist1,
debug = False,
fill = fill,
nang = nang,
simp = simp,
tol = tol,
)
# NOTE: geoms is now the simplified [Multi]Polygon buffer of geoms.
# Add to plot ...
ax.add_geometries(
pyguymer3.geo.extract_polys(geoms),
cartopy.crs.PlateCarree(),
edgecolor = colours[i],
facecolor = "none",
linewidth = 1.0,
)
labels.append(f"{dist2:6,.0f} km")
lines.append(matplotlib.lines.Line2D([], [], color = colours[i]))
print("Plotting ...")
# Configure axis ...
ax.legend(
lines,
labels,
loc = "upper center",
ncol = 4,
)
# Configure figure ...
fg.tight_layout()
# Save figure ...
fg.savefig("find_antipode_v3.png")
matplotlib.pyplot.close(fg)
# Optimize PNG ...
pyguymer3.image.optimize_image(
"find_antipode_v3.png",
strip = True,
)
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