GW default sinkhorn kwargs raises AttributeError

[michalk8]

Not specifying sinkhorn_kwargs in gromov_wasserstein raises an AttributeError; to reproduce:

from ott.core.gromov_wasserstein import gromov_wasserstein
from ott.geometry.geometry import Geometry
import jax.numpy as jnp

x = Geometry(cost_matrix=jnp.ones((10, 10)))
y = Geometry(cost_matrix=jnp.ones((5, 5)))
gromov_wasserstein(x, y, sinkhorn_kwargs={})  # works as expected
gromov_wasserstein(x, y)  # raises the error below

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
/tmp/ipykernel_246820/4027485735.py in <module>
      6 y = Geometry(cost_matrix=jnp.ones((5, 5)))
      7 gromov_wasserstein(x, y, sinkhorn_kwargs={})  # works as expected
----> 8 gromov_wasserstein(x, y)  # raises the error below

~/.miniconda3/envs/cellrank/lib/python3.8/site-packages/ott/core/gromov_wasserstein.py in gromov_wasserstein(geom_x, geom_y, a, b, epsilon, loss, max_iterations, jit, warm_start, sinkhorn_kwargs, **kwargs)
    151     raise ValueError('Unknown loss. Either pass an instance of GWLoss or '
    152                      f'a string among: [{",".join(GW_LOSSES.keys())}]')
--> 153   tau_a = sinkhorn_kwargs.get('tau_a', 1.0)
    154   tau_b = sinkhorn_kwargs.get('tau_b', 1.0)
    155   if tau_a != 1.0 or tau_b != 1.0:

AttributeError: 'NoneType' object has no attribute 'get'

Version 0.1.17.

[marcocuturi]

Thanks! indeed, this was not properly tested. Just wrote pull request #19

[marcocuturi]

Thanks again Michal for noticing this one!