我正在尝试设置Basemap以使用Cylindrical Equal Area投影并将原点放置在特定的lat / lon（这是为了匹配某些输入x / y数据），但似乎设置 lat_0 和 lon_0 参数什么都不做 .
from mpl_toolkits.basemap import Basemap
# Oklahoma bounds
# ('o' = origin at corner of Kingfisher/Logan/Canadian/Oklahoma counties)
lats = {'n': 37.1, 's': 33.6, 'c': 35.5, 'o': 35.726}
lons = {'e': -94.4, 'w': -103.0, 'c': -97.5, 'o': -97.674}
buf = 0.05 # plot buffer size (in degrees)
res = 'c' # map shapes resolution
# projection parameters
proj = 'cea' # cylindrical equal area
lat_ts = lats['c'] # true scale at geographic center
lon_0 = lons['o'] # x=0 at counties corner
lat_0 = lats['o'] # y=0 at counties corner
m = Basemap(projection = proj, lat_ts = lat_ts, resolution = res,
lon_0 = lon_0, lat_0 = lat_0,
urcrnrlon = lons['e'] + buf, urcrnrlat = lats['n'] + buf,
llcrnrlon = lons['w'] - buf, llcrnrlat = lats['s'] - buf*4)
然后检查原点给出：
In [15]: m(0, 0, inverse=True)
Out[15]: (-103.05000000000305, 33.399999999963455)
...这是 Map 边界的左下角，而不是我给 lat_0 和 lon_0 的坐标 . 如果我完全省略lat_0和lon_0，我会得到相同的输出 .
起初，我认为CEA投影可能不支持这些参数，我应该手动移动我的数据，但是the docs claim that lat_0 and lon_0 are used by all projections .
作为一种解决方法，我可以设置偏移量来获得预期结果：
offset = m(lon_0, lat_0)
df['x'], df['y'] = (df.x + offset[0], df.y + offset[1]) # where df is a Pandas dataframe with my data
我现在已经在Basemap GitHub存储库中提交了这个问题 . https://github.com/matplotlib/basemap/issues/192