在Folium地图上添加1KM网格

Question

有没有人能推荐一种方法，在folium地图上添加1公里宽的网格线？这里的folium示例使用的是经纬度间隔，但并没有显示出网格。

import folium

# Bangkok coordinates
center_lat = 13.7563
center_lon = 100.4911

m = folium.Map(location=[center_lat, center_lon], zoom_start=11)


# Interval in degrees (1 kilometer ≈ 0.00694444 degrees)
interval = 0.00694444

# Create grid lines
grid_lines = []

# East-west lines (from -90 to 90 latitude)
for lat in range(-90, 91, int(1 / interval)):
  west_point = (-180, lat)
  east_point = (180, lat)
  grid_lines.append(folium.PolyLine([west_point, east_point], color="black", weight=0.5, opacity=0.5))

# North-south lines (from -180 to 180 longitude)
for lon in range(-180, 181, int(1 / interval)):
  south_point = (lon, -90)
  north_point = (lon, 90)
  grid_lines.append(folium.PolyLine([south_point, north_point], color="black", weight=0.5, opacity=0.5))

# Add lines to the map
for line in grid_lines:
  line.add_to(m)

# Display the map
m

Answer 1

你的网格确实在地图上显示出来了，但效果和你预期的有些不同，因为你用了range，而不是numpy.arange。另外，你在两个循环中反转了每个PolyLine的位置。所以，这里有一个可能的解决办法：

import folium
import numpy as np

CLAT, CLON = 13.7563, 100.4911

m = folium.Map(location=[CLAT, CLON], zoom_start=11)

INTERVAL = 1 / 111  # 1 km to degrees, gives ~0.009

LINE_STYLE = {"color": "black", "weight": 0.5, "opacity": 0.5}

def add_gl(m, s, e, hztl, **kwargs):
    for v in np.arange(s, e + 1, INTERVAL):
        coords = [[v, -180], [v, 180]] if hztl else [[-90, v], [90, v]]
        folium.PolyLine(coords, **kwargs).add_to(m)

add_gl(m, -90, 90, True, **LINE_STYLE)
add_gl(m, -180, 180, False, **LINE_STYLE)

注意：在我的JupyterLab上，地图显示大约花了40秒，操作起来也比较麻烦/慢。所以，如果性能是个问题，你可能需要减少间隔：

INTERVAL = 10 / 111  # 10 kms instead of 1km

# with this, the map takes ~2-5s to render

输出（m）：