Consistent use of abbreviations: attrs, dims, coords

[shoyer]

Right now, we use ds.attrs but the keyword argument is still attributes. We should resolve this inconsistency.

We also use dimensions and coordinates instead of the natural abbreviations dims and coords (although dims is used in the Variable constructor). Should we switch to the abbreviated versions for consistency with attrs?

Note that I switched to attrs in part because of its use in other packages (h5py, pytables and blz). There is not as clear precedent for what to call dimensions and coordinates.

[shoyer]

There is at least one major advantage to using abbreviations: less typing and shorter lines of code!

e.g., compare:

x = xray.Coord('x', np.arange(10))
y = xray.Coord('y', ['a', 'b', 'c'])
arr = xray.DataArray(data, dims=['x', 'y'], coords=[x, y])
'x' in arr.dims

and

x = xray.Coordinate('x', np.arange(10))
y = xray.Coordinate('y', ['a', 'b', 'c'])
arr = xray.DataArray(data, dimensions=['x', 'y'], coordinates=[x, y])
'x' in arr.dimensions

h5py does use dims instead of dimensions: http://docs.h5py.org/en/2.3/high/dims.html and Iris also uses the abbreviations "dim" and "coord".

These are pretty common/obvious abbreviations and they are fundamental enough that I would not worry about imposing them on our users.

Right now, I am leaning toward switching to always using dim/dims and coord/coords/Coord before the 0.2 release. But I don't want to be too hasty about this -- any opinions out there? The counter argument would be that I should stop wasting my time bike-shedding (especially after I've already released this stuff out in the wild).

[shoyer]

I've decided that we do want to switch to using coords and dims.

I have not renamed noncoordinates to noncoords. I'm going to deprecate that property instead (#211).

Also I haven't renamed xray.Coordinate yet -- that will probably become xray.CoordIndex eventually (#197) but for now is OK.

[shoyer]

Actually, I am going to go ahead and rename noncoordinates to noncoords. Deprecating/removing that property will have to wait.

Otherwise everything was done in #194.