Drawing a world heat map using 'cartopy'

Checking 'cartopy' version:

(temp) C:\Users\Ashish Jain>conda list cartopy
# packages in environment at E:\programfiles\Anaconda3\envs\temp:
#
# Name   Version  Build           Channel
cartopy  0.18.0   py37ha46f164_4  conda-forge 

(temp) C:\Users\Ashish Jain>pip show cartopy
Name: Cartopy
Version: 0.18.0
Summary: A cartographic python library with Matplotlib support for visualisation
Home-page: https://scitools.org.uk/cartopy/docs/latest/
Author: UK Met Office
Author-email: None
License: LGPLv3
Location: e:\programfiles\anaconda3\envs\temp\lib\site-packages
Requires: shapely, setuptools, pyshp, six, numpy
Required-by: 

The map we will draw:


Given below is code that draws a World Heat Map showing countries in grey scale:

import cartopy
import cartopy.crs as ccrs
import cartopy.io.shapereader as shpreader
from cartopy.feature import LAND

import matplotlib.pyplot as plt
import matplotlib as mpl
import numpy as np
from datetime import datetime

# Setting the color to shade the countries.
cmap = mpl.cm.Greys # Other color: mpl.cm.Blues

countries = {
    "India": 49,
    "United States": 48,
    "United Arab Emirates": 47,
    "Germany": 46,
    "Singapore": 45,
    "United Kingdom": 44,
    "Russian Federation": 43,
    "Ukraine":42,              
    "Netherlands": 41,
    "Hong Kong": 40,
    "Canada": 39,
    "France": 38,
    "Oman": 37,
    "Australia": 36,
    "Pakistan": 35,
    "Kenya": 34,
    "Malaysia": 33,
    "Saudi Arabia": 32,
    "Turkey": 31,
    "Spain": 30, 
    "Nepal": 29,
    "Qatar": 28,
    "Kuwait": 27,
    "Indonesia": 26,
    "Italy": 25,
    "Sweden": 24,
    "Portugal": 23,
    "Mauritius": 22,
    "New Zealand": 21,
    "Japan": 20,
    "Republic of Korea": 21, # South Korea
    "Barbados": 20, # Not listed in cartopy package
    "Brazil": 19,
    "China": 18,
    "Greece": 17,
    "Poland": 16,
    "Czech Republic": 15,
    "Kazakhstan": 14,
    "Latvia": 13,
    "Ireland": 12,
    "Finland": 11,
    "Peru": 10
}


max_users = float(max(countries.values()))
shapename = 'admin_0_countries'
countries_shp = shpreader.natural_earth(resolution='110m', category='cultural', name=shapename)
ax = plt.axes(projection=ccrs.Robinson())

for country in shpreader.Reader(countries_shp).records():
    name = country.attributes['NAME_LONG']
    
    if name in countries:
        num_users = countries[name]
    else:
        num_users = 1
    
    # ax.add_geometries(country.geometry, ccrs.PlateCarree(), facecolor=cmap(num_users/max_users, 1))
    # TypeError: 'Polygon' object is not iterable
    # name: Fiji, type(country.geometry): [class 'shapely.geometry.multipolygon.MultiPolygon']
    # name: Tanzania, type(country.geometry): [class 'shapely.geometry.polygon.Polygon']
    
    try:
        ax.add_geometries(country.geometry, ccrs.PlateCarree(), facecolor=cmap(num_users/max_users, 1))
    except Exception as e:
        #print(e)
        import shapely.wkt as wkt
        from shapely.geometry import MultiPolygon

        list_str_polygons = [str(country.geometry)]

        c = MultiPolygon(map(wkt.loads, list_str_polygons))
        ax.add_geometries(c, ccrs.PlateCarree(), facecolor=cmap(num_users/max_users, 1))

    ax.add_feature(cartopy.feature.OCEAN, color='lightblue')

#Save the image as a file.
plt.savefig('Audience_' + str(datetime.now()).replace(':', '_') + '.png', transparent=True, dpi=900)  
print("Done") 

Given below is the list of countries recognized by 'cartopy':
Afghanistan
Albania
Algeria
Angola
Antarctica
Argentina
Armenia
Australia
Austria
Azerbaijan
Bahamas
Bangladesh
Belarus
Belgium
Belize
Benin
Bhutan
Bolivia
Bosnia and Herzegovina
Botswana
Brazil
Brunei Darussalam
Bulgaria
Burkina Faso
Burundi
Cambodia
Cameroon
Canada
Central African Republic
Chad
Chile
China
Colombia
Costa Rica
Côte d'Ivoire
Croatia
Cuba
Cyprus
Czech Republic
Dem. Rep. Korea
Democratic Republic of the Congo
Denmark
Djibouti
Dominican Republic
Ecuador
Egypt
El Salvador
Equatorial Guinea
Eritrea
Estonia
eSwatini
Ethiopia
Falkland Islands
Fiji
Finland
France
French Southern and Antarctic Lands
Gabon
Georgia
Germany
Ghana
Greece
Greenland
Guatemala
Guinea
Guinea-Bissau
Guyana
Haiti
Honduras
Hungary
Iceland
India
Indonesia
Iran
Iraq
Ireland
Israel
Italy
Jamaica
Japan
Jordan
Kazakhstan
Kenya
Kosovo
Kuwait
Kyrgyzstan
Lao PDR
Latvia
Lebanon
Lesotho
Liberia
Libya
Lithuania
Luxembourg
Macedonia
Madagascar
Malawi
Malaysia
Mali
Mauritania
Mexico
Moldova
Mongolia
Montenegro
Morocco
Mozambique
Myanmar
Namibia
Nepal
Netherlands
New Caledonia
New Zealand
Nicaragua
Niger
Nigeria
Northern Cyprus
Norway
Oman
Pakistan
Palestine
Panama
Papua New Guinea
Paraguay
Peru
Philippines
Poland
Portugal
Puerto Rico
Qatar
Republic of Korea
Republic of the Congo
Romania
Russian Federation
Rwanda
Saudi Arabia
Senegal
Serbia
Sierra Leone
Slovakia
Slovenia
Solomon Islands
Somalia
Somaliland
South Africa
South Sudan
Spain
Sri Lanka
Sudan
Suriname
Sweden
Switzerland
Syria
Taiwan
Tajikistan
Tanzania
Thailand
The Gambia
Timor-Leste
Togo
Trinidad and Tobago
Tunisia
Turkey
Turkmenistan
Uganda
Ukraine
United Arab Emirates
United Kingdom
United States
Uruguay
Uzbekistan
Vanuatu
Venezuela
Vietnam
Western Sahara
Yemen
Zambia
Zimbabwe