Install torch_scatter from conda instead of pip (#110)

As highlighted by DocMinus in #106, our installation instructions can
fail due to issues with `torch_scatter`. This is because our current
setup is essentially equivalent to `pip install torch-scatter`, which
compiles the library from source, and so depends on having the right
versions of `nvcc` and `gcc`. Instead, this PR shifts the
`torch_scatter` dependency to use `pyg`'s conda channel as opposed to
installation through `pip`.

CHANGELOG.md

@@ -20,6 +20,7 @@ and the project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.
 
 ### Fixed
 
+- Install `torch_scatter` from conda instead of pip ([#110](https://github.com/microsoft/syntheseus/pull/110)) ([@kmaziarz])
 - Remove dependency on `typing_extensions` for python >= 3.8 ([#107](https://github.com/microsoft/syntheseus/pull/107)) ([@austint])
 - Pin further Chemformer dependencies to avoid `torch` reinstallation ([#108](https://github.com/microsoft/syntheseus/pull/108)) ([@kmaziarz])
 - Shift the `pandas` dependency to the external model packages ([#94](https://github.com/microsoft/syntheseus/pull/94)) ([@kmaziarz])

environment_full.yml

@@ -3,13 +3,15 @@ channels:
   - defaults
   - conda-forge
   - pytorch
-  - dglteam       # LocalRetro, RetroKNN
+  - dglteam                 # LocalRetro, RetroKNN
+  - pyg                     # RetroKNN
 dependencies:
-  - dgl-cuda11.3  # LocalRetro, RetroKNN
-  - faiss-gpu     # RetroKNN
+  - dgl-cuda11.3            # LocalRetro, RetroKNN
+  - faiss-gpu               # RetroKNN
   - numpy
   - pip
   - python==3.9.7
   - pytorch=1.10.2=py3.9_cuda11.3_cudnn8.2.0_0
-  - rdchiral_cpp  # MHNreact
+  - pytorch-scatter==2.0.9  # RetroKNN
+  - rdchiral_cpp            # MHNreact
   - rdkit=2021.09.4

pyproject.toml

@@ -41,7 +41,7 @@ graph2edits = ["syntheseus-graph2edits==0.2.0"]
 local-retro = ["syntheseus-local-retro==0.5.0"]
 megan = ["syntheseus-megan==0.1.0"]
 mhn-react = ["syntheseus-mhnreact==1.0.0"]
-retro-knn = ["syntheseus[local-retro]", "torch-scatter"]
+retro-knn = ["syntheseus[local-retro]"]
 root-aligned = ["syntheseus-root-aligned==0.1.0"]
 all-single-step = [
   "syntheseus[chemformer,graph2edits,local-retro,megan,mhn-react,retro-knn,root-aligned]"