def test_howmany():
w, s, e, n = (-106.6495132446289, 25.845197677612305, -93.50721740722656,
36.49387741088867)
zoom = 7
expected = 25
got = ctx.howmany(w, s, e, n, zoom=zoom, verbose=False, ll=True)
assert got == expected
def good_zoom(gdf, low_tiles=1, high_tiles=3):
"Find a good initial zoom level."
crs = gdf.crs
total_bounds = gdf.total_bounds
if crs is None:
raise ValueError
from shapely.geometry import box
mapping_area = gpd.GeoDataFrame(geometry=[box(*total_bounds)], crs=crs).to_crs(epsg=3857)
xmin_, ymin_, xmax_, ymax_ = mapping_area.total_bounds # w s e n
zoom = 1
low_zoom = 1
tiles = {}
tiles[zoom] = howmany = ctx.howmany(xmin_, ymin_, xmax_, ymax_, zoom, verbose=False)
while howmany <= high_tiles:
zoom += 1
if howmany <= low_tiles:
low_zoom += 1
tiles[zoom] = howmany = ctx.howmany(xmin_, ymin_, xmax_, ymax_, zoom, verbose=False)
return zoom - 1 + ((high_tiles - tiles[zoom - 1]) / (howmany - tiles[zoom - 1]))
gdzh["geometry"].total_bounds
# 多个行政区域，多个多边形
gdzh = gpd.read_file("d:/temp/geojsonutf8/中华人民共和国/广东省/珠海市/440400_full.json",
encoding='utf-8')
gdzh = gdzh.to_crs(epsg=3857)
gdzh.plot(figsize=(16, 16))
plt.show()
# 多个行政区域多个多边形的情形，total_bounds对了，用total_bounds
gdzh["geometry"].bounds
gdzh["geometry"].total_bounds
we, se, ee, ne = gdzh["geometry"].total_bounds
# 计算视野需要的zoom参数 -6? 不对
zoom = ctx.tile._calculate_zoom(we, se, ee, ne)
# 计算要下载的瓦片数量，zoom=10:15，11:40, zoom = -6时只需1块 tile
_ = ctx.howmany(we, se, ee, ne, 11, ll=False)
# 下载瓦片图并画图，不接受负值的zoom，ll=True, 火星坐标等，ll=False, 墨卡托坐标,前面已转换成该坐标
# zoom=11是最合适的，就是上面ctx.add_basemap(ax,source=gaodeurl)自动选定的zoom
img, ext = ctx.bounds2img(we, se, ee, ne, 11, ll=False, source=gaodeurl)
fig, ax = plt.subplots(1, figsize=(16, 16))
plt.imshow(img, extent=ext)
# 另存成tif图像文件，程序挂起，？
_ = ctx.bounds2raster(we, se, ee, ne, 'zh.tif', ll=False)
# Orange Geo的离线地图，除美国外都是到省一级
gdf7 = gpd.read_file("D:/Anaconda3/Lib/site-packages/orangecontrib/geo/geojson/admin1-CHN.json",\
encoding='utf-8')
gdf7.plot(figsize=(16, 12))
plt.show()
# 美国的地图边界到郡一级
gdf8 = gpd.read_file("D:/Anaconda3/Lib/site-packages/orangecontrib/geo/geojson/admin2-USA.json",\