issue_comments

I think another solution you could add an aleat microsecond or nanosecond field ... in the datetime index and the index should be different. You could test if there are colision in the index (it means the index<->time is not empty like the sort algorithm, something similar to https://en.wikipedia.org/wiki/Radix_sort)

It is like the reverse of this solution

https://stackoverflow.com/questions/32827169/python-reduce-precision-pandas-timestamp-dataframe/32827432

Add another coordinate could be overloaded and xarray is very powerful to extract slice of time ds.sel(time =slice('2000-06-01', '2000-06-10'))

http://xarray.pydata.org/en/stable/time-series.html#datetime-indexing

I hope it could be useful.

Regards Javier Ruano

El mié., 29 abr. 2020 17:34, Javier Ruano javier.ruanno@gmail.com escribió:

pandas doesn't have that problem import pandas as pd x1=pd.DataFrame([['1','2','3']]) x2=pd.DataFrame([['4','5','6']]) pd.concat([x1,x2],axis=1)

El mié., 29 abr. 2020 a las 17:23, Javier Ruano (javier.ruanno@gmail.com) escribió:

the time is the same. do you have tried to change the second one time index?

El mié., 29 abr. 2020 a las 16:36, Xin Zhang (notifications@github.com) escribió:

It's impossible to concatenate two arrays on same named dimensions with different sizes. MCVE Code Sample

import xarray as xrimport pandas as pd

a = xr.DataArray([0], dims=['x']) b = xr.DataArray([1, 2, 3], dims=['x']) a = a.expand_dims("time") b = b.expand_dims("time") a.coords["time"] = pd.DatetimeIndex(['2020-02-14 05:25:10']) b.coords["time"] = pd.DatetimeIndex(['2020-02-14 05:25:10']) c = xr.concat([a, b], dim='time')print(c)

Expected Output

[0, 1, 2, 3]

Problem Description

File "C:\Users\Xin\Desktop\test_github.py", line 10, in <module> c = xr.concat([a, b], dim='time') File "E:\miniconda3\envs\satpy\lib\site-packages\xarray\core\concat.py", line 135, in concat return f(objs, dim, data_vars, coords, compat, positions, fill_value, join) File "E:\miniconda3\envs\satpy\lib\site-packages\xarray\core\concat.py", line 455, in _dataarray_concat join=join, File "E:\miniconda3\envs\satpy\lib\site-packages\xarray\core\concat.py", line 319, in _dataset_concat *datasets, join=join, copy=False, exclude=[dim], fill_value=fill_value File "E:\miniconda3\envs\satpy\lib\site-packages\xarray\core\alignment.py", line 327, in align % (dim, sizes) ValueError: arguments without labels along dimension 'x' cannot be aligned because they have different dimension sizes: {1, 3}

Versions Output of xr.show_versions() INSTALLED VERSIONS

commit: None python: 3.7.6 | packaged by conda-forge | (default, Jan 7 2020, 21:48:41) [MSC v.1916 64 bit (AMD64)] python-bits: 64 OS: Windows OS-release: 10 machine: AMD64 processor: Intel64 Family 6 Model 158 Stepping 9, GenuineIntel byteorder: little LC_ALL: None LANG: None LOCALE: None.None libhdf5: 1.10.5 libnetcdf: 4.7.3

xarray: 0.15.1 pandas: 1.0.3 numpy: 1.18.1 scipy: 1.4.1 netCDF4: 1.5.3 pydap: None h5netcdf: None h5py: 2.10.0 Nio: None zarr: 2.4.0 cftime: 1.1.1.2 nc_time_axis: None PseudoNetCDF: None rasterio: 1.1.3 cfgrib: None iris: None bottleneck: None dask: 2.10.1 distributed: 2.14.0 matplotlib: 3.2.1 cartopy: 0.17.0 seaborn: 0.10.0 numbagg: None setuptools: 46.1.3.post20200325 pip: 20.0.2 conda: None pytest: None IPython: 7.13.0 sphinx: 2.4.4

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@keewis Thanks! I will try to apply this method and check the results.

you should be able to get this to work by assigning coordinates to x: python In [7]: a = xr.DataArray([0], dims='x', coords={"x": [0]}) ...: b = xr.DataArray([1, 2, 3], dims='x', coords={"x": [0, 1, 2]}) ...: time = pd.DatetimeIndex(['2020-02-14 05:25:10']) ...: a = a.expand_dims("time").assign_coords(time=time) ...: b = b.expand_dims("time").assign_coords(time=time) ...: ...: c = xr.concat([a, b], dim='time') ...: c Out[7]: <xarray.DataArray (time: 2, x: 3)> array([[ 0., nan, nan], [ 1., 2., 3.]]) Coordinates: * x (x) int64 0 1 2 * time (time) datetime64[ns] 2020-02-14T05:25:10 2020-02-14T05:25:10 Note that time does not have unique values which means some operations won't work. Also, xarray can't really do true ragged arrays (i.e. [[0], [1, 2, 3]] is not possible), so we use missing values instead

@dcherian Sorry. I made a mistake in the expected result. It should be [[0], [1, 2, 3]]

umm... your expected result is a concatenation on 'x', which does work...

@JavierRuano The time indexes are same in my real case. Maybe, I have to merge these data if I can't find the solution.

pandas doesn't have that problem import pandas as pd x1=pd.DataFrame([['1','2','3']]) x2=pd.DataFrame([['4','5','6']]) pd.concat([x1,x2],axis=1)

El mié., 29 abr. 2020 a las 17:23, Javier Ruano (javier.ruanno@gmail.com) escribió:

the time is the same. do you have tried to change the second one time index?

El mié., 29 abr. 2020 a las 16:36, Xin Zhang (notifications@github.com) escribió:

It's impossible to concatenate two arrays on same named dimensions with different sizes. MCVE Code Sample

import xarray as xrimport pandas as pd

a = xr.DataArray([0], dims=['x']) b = xr.DataArray([1, 2, 3], dims=['x']) a = a.expand_dims("time") b = b.expand_dims("time") a.coords["time"] = pd.DatetimeIndex(['2020-02-14 05:25:10']) b.coords["time"] = pd.DatetimeIndex(['2020-02-14 05:25:10']) c = xr.concat([a, b], dim='time')print(c)

Expected Output

[0, 1, 2, 3]

Problem Description

File "C:\Users\Xin\Desktop\test_github.py", line 10, in <module> c = xr.concat([a, b], dim='time') File "E:\miniconda3\envs\satpy\lib\site-packages\xarray\core\concat.py", line 135, in concat return f(objs, dim, data_vars, coords, compat, positions, fill_value, join) File "E:\miniconda3\envs\satpy\lib\site-packages\xarray\core\concat.py", line 455, in _dataarray_concat join=join, File "E:\miniconda3\envs\satpy\lib\site-packages\xarray\core\concat.py", line 319, in _dataset_concat *datasets, join=join, copy=False, exclude=[dim], fill_value=fill_value File "E:\miniconda3\envs\satpy\lib\site-packages\xarray\core\alignment.py", line 327, in align % (dim, sizes) ValueError: arguments without labels along dimension 'x' cannot be aligned because they have different dimension sizes: {1, 3}

Versions Output of xr.show_versions() INSTALLED VERSIONS

commit: None python: 3.7.6 | packaged by conda-forge | (default, Jan 7 2020, 21:48:41) [MSC v.1916 64 bit (AMD64)] python-bits: 64 OS: Windows OS-release: 10 machine: AMD64 processor: Intel64 Family 6 Model 158 Stepping 9, GenuineIntel byteorder: little LC_ALL: None LANG: None LOCALE: None.None libhdf5: 1.10.5 libnetcdf: 4.7.3

xarray: 0.15.1 pandas: 1.0.3 numpy: 1.18.1 scipy: 1.4.1 netCDF4: 1.5.3 pydap: None h5netcdf: None h5py: 2.10.0 Nio: None zarr: 2.4.0 cftime: 1.1.1.2 nc_time_axis: None PseudoNetCDF: None rasterio: 1.1.3 cfgrib: None iris: None bottleneck: None dask: 2.10.1 distributed: 2.14.0 matplotlib: 3.2.1 cartopy: 0.17.0 seaborn: 0.10.0 numbagg: None setuptools: 46.1.3.post20200325 pip: 20.0.2 conda: None pytest: None IPython: 7.13.0 sphinx: 2.4.4

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the time is the same. do you have tried to change the second one time index?

El mié., 29 abr. 2020 a las 16:36, Xin Zhang (notifications@github.com) escribió:

It's impossible to concatenate two arrays on same named dimensions with different sizes. MCVE Code Sample

import xarray as xrimport pandas as pd

a = xr.DataArray([0], dims=['x']) b = xr.DataArray([1, 2, 3], dims=['x']) a = a.expand_dims("time") b = b.expand_dims("time") a.coords["time"] = pd.DatetimeIndex(['2020-02-14 05:25:10']) b.coords["time"] = pd.DatetimeIndex(['2020-02-14 05:25:10']) c = xr.concat([a, b], dim='time')print(c)

Expected Output

[0, 1, 2, 3]

Problem Description

File "C:\Users\Xin\Desktop\test_github.py", line 10, in <module> c = xr.concat([a, b], dim='time') File "E:\miniconda3\envs\satpy\lib\site-packages\xarray\core\concat.py", line 135, in concat return f(objs, dim, data_vars, coords, compat, positions, fill_value, join) File "E:\miniconda3\envs\satpy\lib\site-packages\xarray\core\concat.py", line 455, in _dataarray_concat join=join, File "E:\miniconda3\envs\satpy\lib\site-packages\xarray\core\concat.py", line 319, in _dataset_concat *datasets, join=join, copy=False, exclude=[dim], fill_value=fill_value File "E:\miniconda3\envs\satpy\lib\site-packages\xarray\core\alignment.py", line 327, in align % (dim, sizes) ValueError: arguments without labels along dimension 'x' cannot be aligned because they have different dimension sizes: {1, 3}

Versions Output of xr.show_versions() INSTALLED VERSIONS

commit: None python: 3.7.6 | packaged by conda-forge | (default, Jan 7 2020, 21:48:41) [MSC v.1916 64 bit (AMD64)] python-bits: 64 OS: Windows OS-release: 10 machine: AMD64 processor: Intel64 Family 6 Model 158 Stepping 9, GenuineIntel byteorder: little LC_ALL: None LANG: None LOCALE: None.None libhdf5: 1.10.5 libnetcdf: 4.7.3

xarray: 0.15.1 pandas: 1.0.3 numpy: 1.18.1 scipy: 1.4.1 netCDF4: 1.5.3 pydap: None h5netcdf: None h5py: 2.10.0 Nio: None zarr: 2.4.0 cftime: 1.1.1.2 nc_time_axis: None PseudoNetCDF: None rasterio: 1.1.3 cfgrib: None iris: None bottleneck: None dask: 2.10.1 distributed: 2.14.0 matplotlib: 3.2.1 cartopy: 0.17.0 seaborn: 0.10.0 numbagg: None setuptools: 46.1.3.post20200325 pip: 20.0.2 conda: None pytest: None IPython: 7.13.0 sphinx: 2.4.4

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