底图——根据坐标在地图上绘制点；点大小 = 出现次数

Question

我有如下数据集：

import pandas as pd
import numpy as np
df = pd.DataFrame({
    # some ways to create random data
    'Name of City':np.random.choice(["City A", 'City B', 'City C', "City D", "City E", "City F", "City G"], 22),
    'Name of Country':np.random.choice(["Country A", "Country B", "Country C"], 22),
    'lat':np.random.choice([-41, -20, 1, 19, 34, 66, 81], 22),
    'lon': np.random.choice([- 10, 10, 4, 1, -20, 60, 0], 22)
    })

其中纬度/经度表示坐标，城市名称表示所属城市。

我想使用坐标在世界地图上绘制城市坐标 - 点大小取决于该城市在我的数据集中出现的次数，但不知道如何最好地进行。

基于此代码

for idx, row in df.iterrows():
    x, y = row[['lon','lat']]
    plt.annotate(
        str(idx), 
        xy = (x, y), xytext = (-20, 20),
        textcoords = 'offset points', ha = 'right', va = 'bottom',
        bbox = dict(boxstyle = 'round,pad=0.5', fc = 'yellow', alpha = 0.5),
        arrowprops = dict(arrowstyle = '->', connectionstyle = 'arc3,rad=0'))

plt.show()

我设法以某种方式绘制了这些点，但不知道如何将它们放在地图上。有人能指出我正确的方向吗？

非常感谢！

Answer 1

我不太清楚你的坐标应该如何与你的城市名称相关联，但假设每次提到某个城市时都应该使用相同的坐标对。基于此，我在如何生成满足这些要求的数据库以及如何从中提取数据方面有了一些自由。其余的或多或少是直接使用 Basemap:

import pandas as pd
import numpy as np
from matplotlib import pyplot as plt
from mpl_toolkits import basemap

cities = pd.DataFrame({
    'city': ["City A", 'City B', 'City C', "City D", "City E", "City F", "City G"],
    'lat': [-41, -20, 1, 19, 34, 66, 81],
    'lon': [- 10, 10, 4, 1, -20, 60, 0],
})
print(cities)

choices = np.random.choice(range(len(cities.lat)),22)
print(choices)

counts = np.array([list(choices).count(i) for i in range(len(cities.lat))])
print(counts)

fig, ax = plt.subplots()
bmap = basemap.Basemap(ax = ax)

bmap.drawcountries()
bmap.drawcoastlines()

x,y = bmap(cities.lon, cities.lat)

ax.scatter(x, y, s=(2*counts)**2, c='r', label=cities.city)

for idx, row in cities.iterrows():
    x, y = bmap(*row[['lon','lat']])
    plt.annotate(
        str(idx), 
        xy = (x, y), xytext = (-20, 20),
        textcoords = 'offset points', ha = 'right', va = 'bottom',
        bbox = dict(boxstyle = 'round,pad=0.5', fc = 'yellow', alpha = 0.5),
        arrowprops = dict(arrowstyle = '->', connectionstyle = 'arc3,rad=0'))


plt.show()

生成的图像看起来像这样：

底图——根据坐标在地图上绘制点；点大小 = 出现次数

Basemap - draw points on map depending on coordinates; dot size = number of occurences

python-3.x

matplotlib-basemap