错误使用xarray open_mfdataset功能

Question

我想多的netCDF文件具有相同的尺寸相结合，其尺寸如下：

OrderedDict([(u'lat', <type 'netCDF4._netCDF4.Dimension'>: name = 'lat', size = 720 
), (u'lon', <type 'netCDF4._netCDF4.Dimension'>: name = 'lon', size = 1440 
), (u'time', <type 'netCDF4._netCDF4.Dimension'>: name = 'time', size = 96 
), (u'nv', <type 'netCDF4._netCDF4.Dimension'>: name = 'nv', size = 2 
)]) 
OrderedDict([(u'lat', <type 'netCDF4._netCDF4.Dimension'>: name = 'lat', size = 720 
), (u'lon', <type 'netCDF4._netCDF4.Dimension'>: name = 'lon', size = 1440 
), (u'time', <type 'netCDF4._netCDF4.Dimension'>: name = 'time', size = 96 
), (u'nv', <type 'netCDF4._netCDF4.Dimension'>: name = 'nv', size = 2 
)]) 
OrderedDict([(u'lat', <type 'netCDF4._netCDF4.Dimension'>: name = 'lat', size = 720 
), (u'lon', <type 'netCDF4._netCDF4.Dimension'>: name = 'lon', size = 1440 
), (u'time', <type 'netCDF4._netCDF4.Dimension'>: name = 'time', size = 96 
), (u'nv', <type 'netCDF4._netCDF4.Dimension'>: name = 'nv', size = 2 
)]) 
OrderedDict([(u'lat', <type 'netCDF4._netCDF4.Dimension'>: name = 'lat', size = 720 
), (u'lon', <type 'netCDF4._netCDF4.Dimension'>: name = 'lon', size = 1440 
), (u'time', <type 'netCDF4._netCDF4.Dimension'>: name = 'time', size = 96 
), (u'nv', <type 'netCDF4._netCDF4.Dimension'>: name = 'nv', size = 2 
)]) 
OrderedDict([(u'lat', <type 'netCDF4._netCDF4.Dimension'>: name = 'lat', size = 720 
), (u'lon', <type 'netCDF4._netCDF4.Dimension'>: name = 'lon', size = 1440 
), (u'time', <type 'netCDF4._netCDF4.Dimension'>: name = 'time', size = 96 
), (u'nv', <type 'netCDF4._netCDF4.Dimension'>: name = 'nv', size = 2 
)]) 
OrderedDict([(u'lat', <type 'netCDF4._netCDF4.Dimension'>: name = 'lat', size = 720 
), (u'lon', <type 'netCDF4._netCDF4.Dimension'>: name = 'lon', size = 1440 
), (u'time', <type 'netCDF4._netCDF4.Dimension'>: name = 'time', size = 96 
), (u'nv', <type 'netCDF4._netCDF4.Dimension'>: name = 'nv', size = 2 
)]) 
OrderedDict([(u'lat', <type 'netCDF4._netCDF4.Dimension'>: name = 'lat', size = 720 
), (u'lon', <type 'netCDF4._netCDF4.Dimension'>: name = 'lon', size = 1440 
), (u'time', <type 'netCDF4._netCDF4.Dimension'>: name = 'time', size = 96 
), (u'nv', <type 'netCDF4._netCDF4.Dimension'>: name = 'nv', size = 2 
)]) 

然而，在使用open_mfdataset，我得到这个错误：

xr.open_mfdataset(path_file, decode_times=False) 

*** ValueError: cannot infer dimension to concatenate: supply the ``concat_dim`` argument explicitly 

如何解决此错误？我的尺寸中的所有文件

Answer 1

这个错误信息可能是因为你有两个文件具有相同的变量和坐标值，而xarray不知道它是否应该沿着一个新维度堆叠它们，或者只是检查以确保没有值冲突。

如果明确地调用open_mfdataset和concat_dim=None禁用了所有连接尝试，那将会很不错。 This change应该把它变成xarray的下一个版本（v0.9.0）。

在此期间，您可以解决此通过单独打开的文件，并明确将它们合并，例如，

def open_mfdataset_merge_only(paths, **kwargs): 
    if isinstance(paths, basestring): 
     paths = sorted(glob(paths)) 
    return xr.merge([xr.open_dataset(path, **kwargs) for path in paths]) 

在幕后，这基本上是所有open_mfdataset在做什么。

Answer 2

http://xarray.pydata.org/en/stable/generated/xarray.open_mfdataset.html

xarray.open_mfdataset(paths, chunks=None, concat_dim=None, preprocess=None, engine=None, lock=None, **kwargs) 

它看起来像它需要你给一个concat_dim参数相同。从数据推断它有问题。

Dimension to concatenate files along. This argument is passed on to xarray.auto_combine() along with the dataset objects. You only need to provide this argument if the dimension along which you want to concatenate is not a dimension in the original datasets, e.g., if you want to stack a collection of 2D arrays along a third dimension.

这些三维数组是否需要沿着新的第四维堆叠？