In wave.resource.surface_elevation use sum_of_sines method if input spectrum does not have a zero frequency

[simmsa]

Add auto method to wave.resource.surface_elevation to address #308.

The auto method chooses the most computationally efficient surface
elevation computation method based on the input spectrum. auto uses
the sum_of_sines method is a zero frequency is not defined in the input spectrum
index and uses the ifft for all other cases.

[ssolson]

Please do not merge this until after we get #307 into master.

[simmsa]

@akeeste 9b3bc3b changes the strategy for accessing the first frequency index value. Does that method seem more reliable for accessing the first value of the frequency index?

I am seeing some interesting test failures in MHKiT-MATLAB that are within the surface elevation function that I am hoping are not related to this change:

Test:

       function test_surface_elevation_seed(testCase)

           Obj.f = 0.0:0.01/(2*pi):3.5/(2*pi);
           Obj.Tp = 8;
           Obj.Hs = 2.5;
           df = 0.01/(2*pi);
           Trep = 1/df;
           Obj.t = 0:0.05:Trep;

           S = jonswap_spectrum(Obj.f, Obj.Tp, Obj.Hs);
           seednum = 123;
           eta0 = surface_elevation(S, Obj.t);
           eta1 = surface_elevation(S, Obj.t,"seed",seednum);
           assertEqual(testCase,eta0, eta1);
       end

Failure:

================================================================================
Error occurred in Wave_TestResourceSpectrum/test_surface_elevation_seed and it did not run to completion.
    ---------
    Error ID:
    ---------
    'MATLAB:Python:PyException'
    --------------
    Error Details:
    --------------
    Error using dataarray>_check_coords_dims
    Python Error: ValueError: coordinate Frequency has dimensions ('dim_0',), but these are not a subset of the DataArray dimensions ('Frequency',)
    
    Error in dataarray>_infer_coords_and_dims (line 193)
    
    Error in dataarray>__init__ (line 454)
    
    Error in resource>surface_elevation (line 364)
    
    Error in Wave_TestResourceSpectrum/test_surface_elevation_seed (line 43)
                eta0 = surface_elevation(S, Obj.t);
===========================================================

The error appears to be originating from here

MHKiT-Python/mhkit/wave/resource.py

Lines 360 to 370 in 19b4df0

	eta = xr.Dataset()
	for var in S.data_vars:
	if phases is None:
	np.random.seed(seed)
	phase = xr.DataArray(
	data=2 * np.pi * np.random.rand(S[var].size),
	dims="Frequency",
	coords={"Frequency": f},
	)
	else:
	phase = phases[var]

It seems like xarray is really picky about the names of the dimensions. In the MATLAB surface_elevation function we pass a dataframe into the wave.resource.surface_elevation function. Any thoughts? Getting this far I don't think this is an issue related to this PR.

[simmsa]

@ssolson, sorry for the poor timing of this PR. This does not need to be included in the latest release. Thank you!

[simmsa]

@akeeste this is good to go now! The test failure in MHKiT-MATLAB is unrelated to this change. #313 adds a fix for the dim_0 error.

[ssolson]

Hey @simmsa apologies for messing this PR up. This should be easier going forward but there were some inconsistencies in how PR merged strategies were applied by the final merge author which made this messier. I perhaps should have just accepted the mess but instead decided to squash into master. My preferred strategy going forward is to squash PRs to develop and merge by ort into master.

To ensure master and develop are even I did a force rebase on origin develop.

That said can you either rebase or resubmit this PR?
The official approach is to:

git checkout develop
git fetch origin
git reset --hard origin/develop

git checkout feature-branch
git rebase develop
git push user-fork feature-branch --force

That said rebasing may be extremely painful and it might be easier to just start from the new develop and remake the changes. Apologies for the trouble on this.

[ssolson]

@simmsa when you get a chance could you look to resolve the merge conflicts to we can close this PR?