个人博客页面链接：http://www.shihao.online/（django搭建的个人博客，还在完善中）

#encoding:utf-8

import pygal
import json
from pygal_maps_world.i18n import COUNTRIES
from pygal.style import RotateStyle     #设置颜色的模块
from pygal.style import LightColorizedStyle    #加亮颜色主题


def get_country_code(country_name):
    '''根据指定的国家， 返回Pygal使用的两个字母的国别码'''
    for code, name in COUNTRIES.items():    #遍历键值对
        if name == country_name:
            return code
    #如果找不到指定的国家， 就返回None
    return None

#将数据加载到一个列表中
filename = 'population_data.json'
with open(filename) as f:
    pop_data = json.load(f)

#创建一个包含人口数量的字典
cc_populations = {}
for pop_dict in pop_data:
    if pop_dict['Year'] == '2010':
        country_name = pop_dict['Country Name']
        population = int(float(pop_dict['Value']))
        #print(country_name + ": " + str(population))
        code = get_country_code(country_name)
        if code:
            cc_populations[code] = population

#根据人口数量将所有的国家分成三组
cc_pops_1, cc_pops_2, cc_pops_3 = {}, {}, {}
for cc, pop in cc_populations.items():
    if pop < 10000000:
        cc_pops_1[cc] =pop
    elif pop < 1000000000:
        cc_pops_2[cc] = pop
    else:
        cc_pops_3[cc] = pop

wm_style = RotateStyle("#336699", base_style = LightColorizedStyle)   #红绿蓝
wm = pygal.maps.world.World(style = wm_style)   #创建一个world实例
wm.title = 'World Population in 2010, by Country'
wm.add("0-10m", cc_pops_1)    #add()接受一个标签和一个列表或者字典
wm.add("10m-1bn", cc_pops_2)
wm.add(">1bn", cc_pops_3)
wm.render_to_file('World_Population.svg')