通过openstreetmap API获取国家边界

Question

我想画一张欧洲地图。为此，我需要将国家轮廓作为多边形。为此，我想使用 openstreetmap API。我尝试了一下，overpy但我对单个国家/地区的结果需要 10 分钟才能执行，而且看起来不正确（似乎这些方法不适合在一起）。到目前为止我的代码：import matplotlib.pyplot as pltimport overpyapi = overpy.Overpass()result=api.query("area['name:en'='Denmark']->.country;rel['name:en'='Denmark']['type'='boundary']['admin_level'='2'];(way(r)['maritime' != 'yes'](40,-10,70,80);way(area.country)['natural'='coastline'](40,-10,70,80););out geom;")x=[]y=[]i=0for way in result.ways:    print(f"way {i} of {len(result.ways)}")    i=i+1    for node in way.get_nodes(True):        x.append(float(node.lon))        y.append(float(node.lat))plt.plot(x, y,label=str(way.id))plt.show()我走在正确的轨道上还是有更好的解决方案？谢谢！

Answer 1

我认为这没关系，只需使用点而不是线。对于长时间运行我也没有解决方案。

import matplotlib.pyplot as plt

import overpy

api = overpy.Overpass()

result=api.query("area['name:en'='Denmark']->.country;rel['name:en'='Denmark']['type'='boundary']['admin_level'='2'];(way(r)['maritime' != 'yes'](40,-10,70,80);way(area.country)['natural'='coastline'](40,-10,70,80););out geom;")

x=[]

y=[]

i=0

for way in result.ways:

    print(f"way {i} of {len(result.ways)}")

    if 'natural' in way.tags and way.tags['natural']=='coastline' and len(way.get_nodes(True))>0: #just a test

        i=i+1

        for node in way.get_nodes(True):

            print (f'lon: {float(node.lon):3.4f}; lat: {float(node.lat):3.4f}')

            x.append(float(node.lon))

            y.append(float(node.lat))

plt.plot(x, y, 'o',label=str(way.id))

plt.show()

由于多边形而编辑：

import json

import matplotlib.pyplot as plt

import overpy

def getData():

    api = overpy.Overpass()

    result = api.query("area['name:en'='Denmark']->.country;rel['name:en'='Denmark']['type'='boundary']['admin_level'='2'];(way(r)['maritime' != 'yes'](40,-10,70,80);way(area.country)['natural'='coastline'](40,-10,70,80););out geom;")

    x = []

    y = []

    i = 0

    for way in result.ways:

        print(f"way {i} of {len(result.ways)}")

        # just a test

        if 'natural' in way.tags and way.tags['natural'] == 'coastline' and len(way.get_nodes(True)) > 0:

            i = i+1

            x1 = []

            y1 = []

            for node in way.get_nodes(True):

                print(

                    f'lon: {float(node.lon):3.4f}; lat: {float(node.lat):3.4f}')

                x1.append(float(node.lon))

                y1.append(float(node.lat))

            x.append(x1)

            y.append(y1)

    xy = [x, y]

    with open('data.txt', 'w') as f:

        json.dump(xy, f)

def readDate():

    with open('data.txt', 'r') as f:

        return json.load(f)

getData()

data = readDate()

last = None

first = None

d = []

k = [[], []]

m = []

while(len(data[0]) > 0):

    if last == None and first == None:   # Make sure that there are no "ways" at the beginning or end that match the line.

        last = [data[0][0][-1], data[1][0][-1]] # Get first and last point of a new line

        first = [data[0][0][0], data[1][0][0]]

        k[0] = k[0] + data[0][0] # Start the new line

        k[1] = k[1] + data[1][0]

        data[0].pop(0) # Drop the way

        data[1].pop(0) 

    for j in range(0, len(data[0])): # Check all lines

        if first == [data[0][j][-1], data[1][j][-1]]: # If the first ...

            print(f'First {first[0]}; {first[1]}')

            k = [data[0][j] + k[0], data[1][j] + k[1]]

            first = [data[0][j][0], data[1][j][0]]

            data[0].pop(j)

            data[1].pop(j)

            break

        if last == [data[0][j][0], data[1][j][0]]: # or the last point continue the current line

            print(f'Last  {last[0]}; {last[1]}')

            k = [k[0] + data[0][j], k[1] + data[1][j]] # Add the segment to the new line

            last = [data[0][j][-1], data[1][j][-1]] # Set the point new last point

            data[0].pop(j) # Drop the way

            data[1].pop(j)

            break

        if j == len(data[0])-1: # When the for-loop reaches the end, there is no "way" that continue the line

            m.append(k)

            k = [[], []]

            first = None

            last = None

    if len(data[0]) == 1: # If the last remaining line is a small island, just add it.

        k = [data[0][0], data[1][0]]

        m.append(k)

        data[0].pop(0)

        data[1].pop(0)

for i in range(0, len(m)):

    plt.plot(m[i][0], m[i][1], label=f'Denmark')

plt.show()

该算法以尽可能创建多边形的方式排列 API 中的“方式”。