issue_comments: 82034427

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https://github.com/pydata/xarray/issues/374#issuecomment-82034427 https://api.github.com/repos/pydata/xarray/issues/374 82034427 MDEyOklzc3VlQ29tbWVudDgyMDM0NDI3 167164 2015-03-17T02:04:17Z 2015-03-17T02:04:17Z NONE

Ah, cool, that looks good, however, I think there might be a bug somewhere. Here's what I was getting originally:

``` In [62]: new_data['time'].encoding

Out[62]: {}

In [60]: new_data.to_netcdf('data/tumba_site_mean_2_year.nc') ```

resulted in:

``` $ ncdump ../projects/synthetic_forcings/data/tumba_site_mean_2_year.nc|grep time --context=2 netcdf tumba_site_mean_2_year { dimensions: time = 35088 ; y = 1 ; x = 1 ; variables: ... float time(time) ; time:calendar = "proleptic_gregorian" ; time:units = "minutes since 2000-01-01 00:30:00" ; ...

time = 0, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360, 390, 420, 450, 480, 510, 540, 570, 600, 630, 660, 690, 720, 750, 780, 810, 840, ```

And if I copy the encoding from the original file, as it was loaded:

``` In [65]: new_data['time'].encoding = data['time'].encoding

In [66]: new_data['time'].encoding

Out[66]: {'dtype': dtype('>f8'), 'units': 'seconds since 2002-01-01 00:30:00'}

In [67]: new_data.to_netcdf('data/tumba_site_mean_2_year.nc') ```

results in

``` $ ncdump ../projects/synthetic_forcings/data/tumba_site_mean_2_year.nc|grep time --context=1 dimensions: time = 35088 ; y = 1 ; -- variables: ... double time(time) ; time:calendar = "proleptic_gregorian" ; time:units = "seconds since 2002-01-01T00:30:00" ;

... time = -63158400, -63156600, -63154800, -63153000, -63151200, -63149400, -63147600, -63145800, -63144000, -63142200, -63140400, -63138600, ```

Now the units are right, but the values are way off. I can't see anything obvious missing from the encoding, compared to the xray docs, but I'm not sure how it works.

Also, since seconds are the base SI unit for time, I think it would be sensible to use seconds by default, if no encoding is given.

 
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