issues: 293725143

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293725143 MDU6SXNzdWUyOTM3MjUxNDM= 1878 dtype kwargs of aggregation methods not passed to numpy function 5638829 closed 0     3 2018-02-01T23:47:58Z 2018-02-02T00:06:02Z 2018-02-01T23:58:08Z NONE      

Hi,

I'm trying to pass dtype= as kwargs to some aggregation methods, but it seems that the argument is ignored. See the example below.

```python import xarray as xr import numpy as np from datetime import datetime import datetime as dt

arr = np.random.randint(0, 10000, size=(20, 1000, 1000), dtype=np.int16) date_list = [datetime(2018, 1, 1) + dt.timedelta(delta) for delta in range(20)] xarr = xr.DataArray(arr, dims=['time', 'x', 'y'], coords={'time': date_list}) xset = xr.Dataset({'blue': xarr, 'green': xarr, 'red': xarr}) print(xset)

<xarray.Dataset>

Dimensions: (time: 20, x: 1000, y: 1000)

Coordinates:

* time (time) datetime64[ns] 2018-01-01 2018-01-02 2018-01-03 ...

Dimensions without coordinates: x, y

Data variables:

blue (time, x, y) int16 1946 9194 1563 8318 938 8498 7999 6609 6275 ...

red (time, x, y) int16 1946 9194 1563 8318 938 8498 7999 6609 6275 ...

green (time, x, y) int16 1946 9194 1563 8318 938 8498 7999 6609 6275 ...

xset_mean = xset.mean('time', keep_attrs=True, dtype=np.int16) print(xset_mean)

<xarray.Dataset>

Dimensions: (x: 1000, y: 1000)

Dimensions without coordinates: x, y

Data variables:

blue (x, y) float64 5.46e+03 4.717e+03 5.959e+03 4.31e+03 4.865e+03 ...

red (x, y) float64 5.46e+03 4.717e+03 5.959e+03 4.31e+03 4.865e+03 ...

green (x, y) float64 5.46e+03 4.717e+03 5.959e+03 4.31e+03 4.865e+03 ...

Pure numpy

arr_mean = arr.mean(axis=0, dtype=np.int16) print(arr_mean.dtype)

int16

```

INSTALLED VERSIONS ------------------ commit: None python: 3.5.2.final.0 python-bits: 64 OS: Linux OS-release: 4.4.0-104-generic machine: x86_64 processor: x86_64 byteorder: little LC_ALL: en_US.UTF-8 LANG: en_US.UTF-8 LOCALE: en_US.UTF-8 xarray: 0.10.0 pandas: 0.22.0 numpy: 1.14.0 scipy: None netCDF4: 1.3.1 h5netcdf: None Nio: None bottleneck: None cyordereddict: None dask: 0.16.0 matplotlib: None cartopy: None seaborn: None setuptools: 38.4.0 pip: 9.0.1 conda: None pytest: None IPython: None sphinx: None 
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   completed 13221727 issue

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