Add a "drop" option to squeeze

[shoyer]

If True, squeezed dimensions should be dropped from the resulting object (instead of being retained as scalar)

[naught101]

Not sure if it's worth a separate feature request, but it'd be great to have a drop option in .isel() as well. For example:

>>> ds
<xarray.Dataset>
Dimensions:  (lat: 360, lon: 720, time: 2928)
Coordinates:
  * lon      (lon) float64 0.25 0.75 1.25 1.75 2.25 2.75 3.25 3.75 4.25 4.75 ...
  * lat      (lat) float64 -89.75 -89.25 -88.75 -88.25 -87.75 -87.25 -86.75 ...
  * time     (time) datetime64[ns] 2012-01-01 2012-01-01T03:00:00 ...
Data variables:
    dswrf    (time, lat, lon) float64 446.5 444.9 445.3 447.8 452.4 456.3 ...

>>> ds.isel(lat=0, lon=0, drop=True)
<xarray.Dataset>
Dimensions:  (time: 2928)
Coordinates:
  * time     (time) datetime64[ns] 2012-01-01 2012-01-01T03:00:00 ...
Data variables:
    dswrf    (time) float64 446.5 444.9 445.3 447.8 452.4 456.3 ...

This would be useful for making .to_dataframe() more efficient, too, I suspect, since I have to currently do forcing.isel(lat=0, lon=0).to_dataframe()[['dswrf']] to remove the (constant) lat/lon data from the dataframe.

[shoyer]

@naught101 Yes, I think that would be useful.

[naught101]

Awesome, thanks shoyer! :)