Specified grid spacing for ShapeTanimotoDistance is ignored.

[greglandrum]

Discussed in #4363

^{Originally posted by ljmartin July 27, 2021}
Hi all,
Looking for some help interpreting the usage of ShapeTanimotoDist. I'd like to see the effect of finer grid spacing. Changing the gridSpacing parameter apparently doesn't change the results:

from rdkit import Chem
from rdkit.Chem.rdShapeHelpers import ShapeTanimotoDist

testmol = Chem.MolFromSmiles('CCCC')
testmolH = Chem.AddHs(testmol)
AllChem.EmbedMultipleConfs(testmolH, 2)

print('change grid spacing:')
for gs in [0.0001, 0.001, 0.01, 0.1, 1]:
    print(ShapeTanimotoDist(testmolH, testmolH, 0,1,gridSpacing=gs))

which returns:

change grid spacing
0.4034090909090909
0.4034090909090909
0.4034090909090909
0.4034090909090909
0.4034090909090909

Am I missing something? Thanks!
Lewis