xarray 将新的 2D 坐标设置为维度

问题描述

我在 x/y 网格上有一个海面温度值的 xarray 数据集。 x 和 y 是一维向量坐标，所以它看起来像这个最小的例子：

<xarray.Dataset>
Dimensions:  (x: 10,y: 10)
Coordinates:
  * x        (x) int64 0 1 2 3 4 5 6 7 8 9
  * y        (y) int64 0 1 2 3 4 5 6 7 8 9
Data variables:
    data     (x,y) float64 0.559 0.01037 0.1562 ... 0.08778 0.3272 0.8661

我能够从这个 x/y 网格计算纬度/经度，输出是 2 个二维数组。我可以将它们添加为坐标 ds.assign_coords:

<xarray.Dataset>
Dimensions:  (x: 10,y: 10)
Coordinates:
  * x        (x) int64 0 1 2 3 4 5 6 7 8 9
  * y        (y) int64 0 1 2 3 4 5 6 7 8 9
    lat      (x,y) float64 30.0 30.0 30.0 30.0 30.0 ... 39.0 39.0 39.0 39.0
    lon      (x,y) float64 -120.0 -119.0 -118.0 -117.0 ... -113.0 -112.0 -111.0
Data variables:
    data     (x,y) float64 0.559 0.01037 0.1562 ... 0.08778 0.3272 0.8661

但我想 .sel 沿着纬度/经度的切片。这目前是不可能的，因为我收到错误：

ds.sel(lat=slice(32,36),lon=slice(-118,-115))

ValueError                                Traceback (most recent call last)
<ipython-input-20-28c79202d5f3> in <module>
----> 1 ds.sel(lat=slice(32,-115))

~/.local/lib/python3.8/site-packages/xarray/core/dataset.py in sel(self,indexers,method,tolerance,drop,**indexers_kwargs)
   2363         """
   2364         indexers = either_dict_or_kwargs(indexers,indexers_kwargs,"sel")
-> 2365         pos_indexers,new_indexes = remap_label_indexers(
   2366             self,indexers=indexers,method=method,tolerance=tolerance
   2367         )

~/.local/lib/python3.8/site-packages/xarray/core/coordinates.py in remap_label_indexers(obj,**indexers_kwargs)
    419     }
    420 
--> 421     pos_indexers,new_indexes = indexing.remap_label_indexers(
    422         obj,v_indexers,tolerance=tolerance
    423     )

~/.local/lib/python3.8/site-packages/xarray/core/indexing.py in remap_label_indexers(data_obj,tolerance)
    256     new_indexes = {}
    257 
--> 258     dim_indexers = get_dim_indexers(data_obj,indexers)
    259     for dim,label in dim_indexers.items():
    260         try:

~/.local/lib/python3.8/site-packages/xarray/core/indexing.py in get_dim_indexers(data_obj,indexers)
    222     ]
    223     if invalid:
--> 224         raise ValueError(f"dimensions or multi-index levels {invalid!r} do not exist")
    225 
    226     level_indexers = defaultdict(dict)

ValueError: dimensions or multi-index levels ['lat','lon'] do not exist

所以我的问题是：如何将 data 的维度更改为 (lon: (10,10),lat: (10,10)) 而不是 (x: 10,y: 10？这甚至可能吗？

重现示例数据集的代码：

import numpy as np
import xarray as xr

# Create sample data
data = np.random.rand(10,10)
x = y = np.arange(10)

# Set up dataset
ds = xr.Dataset(
    data_vars = dict(
        data = (["x","y"],data)
    ),coords= {
        "x" : x,"y" : y
    }
)

# Create example lat/lon and assign to dataset
lon,lat = np.meshgrid(np.linspace(-120,-111,np.linspace(30,39,10))

ds = ds.assign_coords({
    "lat": (["x",lat),"lon": (["x",lon)
})

解决方法

暂无找到可以解决该程序问题的有效方法，小编努力寻找整理中！

如果你已经找到好的解决方法，欢迎将解决方案带上本链接一起发送给小编。

小编邮箱:dio#foxmail.com (将#修改为@）

numpy python python-xarray