Accounts for selenocysteine in sidechain torsion angle computation (#316

)

* add PSW to nonstandard residues

* improve insertion and non-standard residue handling

* refactor chain selection

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* remove unused verbosity arg

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* fix chain selection in tests

* fix chain selection in tutorial notebook

* fix notebook chain selection

* fix chain selection typehint

* Update changelog

* Add NLW to non-standard residues

* add .ent support

* add entry for construction from dataframe

* add missing stage arg

* improve obsolete mapping retrieving to include entries with no replacement

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* update changelog

* add transforms to foldcomp datasets

* fix jaxtyping syntax

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* Update changelog

* fix double application of transforms

* improve foldcomp data loading performance

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* remove unused imports

* linting

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* Update changelog

* add B factors to FC parsing output

* bugfix to alpha & kappa angle embedding

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* update changelog

* handle selenocysteine in sidechain torsion angle computation

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---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

graphein/protein/tensor/angles.py

@@ -70,10 +70,18 @@ def _extract_torsion_coords(
     res_atoms = []
     idxs = []
 
+    # Whether or not the protein contains selenocysteine
+    selenium = coords.shape[1] == 38
+
     # Iterate over residues and grab indices of the atoms for each Chi angle
     for i, res in enumerate(res_types):
         res_coords = []
-        for angle_coord_set in CHI_ANGLES_ATOMS[res]:
+
+        angle_groups = CHI_ANGLES_ATOMS[res]
+        if not selenium and res == "SEC":
+            angle_groups = []
+
+        for angle_coord_set in angle_groups:
             res_coords.append([ATOM_NUMBERING[i] for i in angle_coord_set])
             idxs.append(i)
         res_atoms.append(torch.tensor(res_coords, device=coords.device))
@@ -115,6 +123,9 @@ def sidechain_torsion(
     :return: _description_
     :rtype: Union[TorsionTensor, Tuple[TorsionTensor, torch.Tensor]]
     """
+    # Whether or not the protein contains selenocysteine
+    selenium = coords.shape[1] == 38
+
     idxs, coords = _extract_torsion_coords(coords, res_types)
     angles = _dihedral_angle(
         coords[:, 0, :].unsqueeze(1),
@@ -139,7 +150,11 @@ def sidechain_torsion(
     res_types = copy.deepcopy(res_types)
     res_types.reverse()
     for res in res_types:
-        if res in ["ALA", "GLY", "UNK"]:
+        PAD_RESIDUES = ["ALA", "GLY", "UNK"]
+        if not selenium:
+            PAD_RESIDUES.append("SEC")
+
+        if res in PAD_RESIDUES:
             post_pad_len += 1
         else:
             break