如何在 geojson 周围画一个圆？

Question

我有一个基于 geojson 的多边形。如何绘制一个圆以使 geojson 适合圆内？

我尝试过谷歌，但运气不佳。

Answer 1

在不知道您的

.geojson

文件是什么样子的情况下，我无法为您提供更具体的解决方案。假设您的

.geojson

看起来像这样：

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              0,
              0
            ],
            [
              0,
              4
            ],
            [
              4,
              4
            ],
            [
              4,
              0
            ],
            [
              0,
              0
            ]
          ]
        ]
      },
      "properties": {}
    },
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [
          2.0,
          2.0
        ]
      },
      "properties": {
        "radius": 2.8284271247461903
      }
    }
  ]
}

解决方案如下：

import geojson
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.patches import Polygon as mpl_polygon, Circle as mpl_circle

# Load the GeoJSON file
with open('polygon_and_circle.geojson', 'r') as f:
    geojson_data = geojson.load(f)

# Extract the coordinates of the first polygon
polygon_coordinates = np.array(geojson_data['features'][0]['geometry']['coordinates'][0])

# Calculate the bounding box of the polygon
minx, miny = np.min(polygon_coordinates, axis=0)
maxx, maxy = np.max(polygon_coordinates, axis=0)

# Calculate the center point
center_x = (minx + maxx) / 2
center_y = (miny + maxy) / 2

# Calculate the radius based on the distance from the center to the farthest vertex
radius = max(np.sqrt((maxx - center_x)**2 + (maxy - center_y)**2),
             np.sqrt((minx - center_x)**2 + (maxy - center_y)**2),
             np.sqrt((maxx - center_x)**2 + (miny - center_y)**2),
             np.sqrt((minx - center_x)**2 + (miny - center_y)**2))

# Create the plot
fig, ax = plt.subplots()

# Plot the polygon
polygon_patch = mpl_polygon(polygon_coordinates, edgecolor='green', fill=False)
ax.add_patch(polygon_patch)

# Plot the circle
circle_patch = mpl_circle((center_x, center_y), radius, edgecolor='red', fill=False)
ax.add_patch(circle_patch)

# Set plot limits
ax.set_xlim(minx - radius, maxx + radius)
ax.set_ylim(miny - radius, maxy + radius)

# Show the plot
plt.xlabel('Longitude')
plt.ylabel('Latitude')
plt.title('Polygon with Enclosing Circle')
plt.gca().set_aspect('equal', adjustable='box')
plt.grid()
plt.show()

输出：

希望有帮助！