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script to find the antipode to all UK and US territories
# This is the top-most EditorConfig file ...
root = true
# Configure all files ...
charset = utf-8
end_of_line = lf
indent_size = 4
indent_style = space
insert_final_newline = true
tab_width = 4
trim_trailing_whitespace = true
# Configure Makefiles ...
indent_style = tab
# OS generated files ...
# Hide compiled code ...
# Hide output of PyLint/ShellCheck ...
# Ignore compiler generated files ...
# Hide large datasets ...


This Gist was made for a blog post on my web site.


This Gist requires the following Python modules to be installed and available in your PYTHONPATH.

This Gist uses some Global Self-Consistent Hierarchical High-Resolution Geography resources and some Natural Earth resources via the cartopy module. If they do not exist on your system then cartopy will download them for you in the background. Consequently, a working internet connection may be required the first time you run this Gist.

#!/usr/bin/env python3
# Use the proper idiom in the main module ...
# NOTE: See
if __name__ == "__main__":
# Import standard modules ...
import os
# Import special modules ...
import cartopy
"cache_dir" : os.path.expanduser("~/.local/share/cartopy_cache"),
raise Exception("\"cartopy\" is not installed; run \"pip install --user Cartopy\"") from None
import matplotlib
"backend" : "Agg", # NOTE: See
"figure.dpi" : 300,
"figure.figsize" : (9.6, 7.2), # NOTE: See
"font.size" : 8,
import matplotlib.pyplot
raise Exception("\"matplotlib\" is not installed; run \"pip install --user matplotlib\"") from None
import shapely
import shapely.geometry
import shapely.ops
raise Exception("\"shapely\" is not installed; run \"pip install --user Shapely\"") from None
# Import my modules ...
import pyguymer3
import pyguymer3.geo
import pyguymer3.image
raise Exception("\"pyguymer3\" is not installed; you need to have the Python module from located somewhere in your $PYTHONPATH") from None
# **************************************************************************
# List countries to find the antipodes of ...
# NOTE: Ignore Antarctica.
avoids = [
"United Kingdom",
"Br. Indian Ocean Ter.",
"British Virgin Is.",
"Cayman Is.",
"Falkland Is.",
"Pitcairn Is.",
"S. Geo. and the Is.",
"Saint Helena",
"Turks and Caicos Is.",
"United States of America",
"American Samoa",
"Marshall Is.",
"N. Mariana Is.",
"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 =
category = "cultural",
name = "admin_0_countries",
resolution = res,
# **************************************************************************
# **************************************************************************
# Create empty list ...
geoms = []
# Loop over records ...
for record in
# 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:
# 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)
# **************************************************************************
# 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
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]
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(
debug = False,
fill = fill,
nang = nang,
simp = simp,
tol = tol,
# NOTE: geoms is now the simplified [Multi]Polygon buffer of geoms.
# Add to plot ...
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 ...
loc = "upper center",
ncol = 4,
# Configure figure ...
# Save figure ...
# Optimize PNG ...
strip = True,
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