issues: 349855157

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349855157 MDU6SXNzdWUzNDk4NTUxNTc= 2362 Wrong behavior of DataArray.resample 6815844 closed 0     0 2018-08-13T00:02:47Z 2019-10-22T19:42:08Z 2019-10-22T19:42:08Z MEMBER      

From #2356, I noticed resample and groupby works nice for Dataset but not for DataArray

Code Sample, a copy-pastable example if possible

```python In [14]: import numpy as np ...: import xarray as xr ...: import pandas as pd ...: ...: time = pd.date_range('2000-01-01', freq='6H', periods=365 * 4) ...: ds = xr.Dataset({'foo': (('time', 'x'), np.random.randn(365 * 4, 5)), 'time': time, ...: 'x': np.arange(5)})

In [15]: ds Out[15]: <xarray.Dataset> Dimensions: (time: 1460, x: 5) Coordinates: * time (time) datetime64[ns] 2000-01-01 ... 2000-12-30T18:00:00 * x (x) int64 0 1 2 3 4 Data variables: foo (time, x) float64 -0.6916 -1.247 0.5376 ... -0.2197 -0.8479 -0.6719 ``ds.resample(time='M').mean()['foo']andds['foo'].resample(time='M').mean()['foo']` should be the same, but currently not

python In [16]: ds.resample(time='M').mean()['foo'] Out[16]: <xarray.DataArray 'foo' (time: 12, x: 5)> array([[-0.005705, 0.018112, 0.22818 , -0.11093 , -0.031283], [-0.007595, 0.040065, -0.099885, -0.123539, -0.013808], [ 0.112108, -0.040783, -0.023187, -0.107504, 0.082927], [-0.007728, 0.031719, 0.155191, -0.030439, 0.095658], [ 0.140944, -0.050645, 0.116619, -0.044866, -0.242026], [ 0.029198, -0.002858, 0.13024 , -0.096648, -0.170336], [-0.062954, 0.116073, 0.111285, -0.009656, -0.164599], [ 0.030806, 0.051327, -0.031282, 0.129056, -0.085851], [ 0.099617, -0.021049, 0.137962, -0.04432 , 0.050743], [ 0.117366, 0.24129 , -0.086894, 0.066012, 0.004789], [ 0.063861, -0.015472, 0.069508, 0.026725, -0.124712], [-0.058683, 0.154761, 0.028861, -0.139571, -0.037268]]) Coordinates: * time (time) datetime64[ns] 2000-01-31 2000-02-29 ... 2000-12-31 * x (x) int64 0 1 2 3 4

python In [17]: ds['foo'].resample(time='M').mean() # dimension x is gone Out[17]: <xarray.DataArray 'foo' (time: 12)> array([ 0.019675, -0.040952, 0.004712, 0.04888 , -0.015995, -0.022081, -0.00197 , 0.018811, 0.044591, 0.068512, 0.003982, -0.01038 ]) Coordinates: * time (time) datetime64[ns] 2000-01-31 2000-02-29 ... 2000-12-31

Problem description

resample should work identically for DataArray and Dataset

Expected Output

python ds.resample(time='M').mean()['foo'] == ds['foo'].resample(time='M').mean()

 
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