pylibcugraphops-cu11 24.12.0
pylibcugraphops - GPU Graph Neural Network operations
License: Apache 2.0
Requires Python: >=3.10

# pylibcugraphops

**pylibcugraphops** is a wrapper around **cugraph-ops** and provides framework-agnostic and lightweight Python-bindings for the custom graph operators of cugraph-ops. For more information on the implemented functionality, check the corresponding documentations.

## Structure
In terms of structure, the bindings somewhat follow the guidelines of cugraph-ops. The main difference is that pylibcugraphops is more focused on providing reasonable submodules and thus the overall structure is rather flat. The core functionality is placed under `pylibcugraphops.operators` similar to the C++ API with the `<cugraph-ops/operators>` namespace. This includes basic aggregation operators (e.g. for GraphSAGE), specialized operators (e.g. for RGCN), and operators performing pooling-like operations (e.g. readout operations aggregating from a graph-to-scalar level). While the C++ API has a further distinction into operators for message flow graphs and other kinds of graphs which can be represented through CSC, the `pylibcugraphops.operators` is kept as a flat submodule with the function names making the disctiontion.

## Naming Convention
The name of exposed operators and corresponding files should be self-explanatory to provide an easy overview of all relevant charateristics. Therefore, we adopt the following naming convention for operators.

`<operator family>_<graph type>_<"direction">_(<operator specification>_)<[fwd|bwd|bwd_rev|...]`

Examples
- `agg_simple_csc_bwd`
- `pool_csc_n2s_bwd`
- `agg_hg_basis_mfg_n2n_post_bwd`

Support for different datatypes is achieved through overloading and thus usually not explicitly part of operator names.

### Explanation of Individual Parts

- `<operator family>` denotes the underlying operator, we currently have
    - `agg_simple`: basic aggregator performing a mean/sum/min/max reduction of the specified set
    - `agg_concat`: like `agg_simple` but additionally concatenates the self representation of each set member
    - `agg_dmpnn`: implmements the DMPNN edge-to-edge aggregation
    - `pool`: sum/mean/min/max pooling, e.g. node-to-scalar readout
    - `hg_basis`: heterogenous aggregation using different edge types and potentially using a basis decomposition
    - `mha_gat`: multi-headed attention aggregation, in this case GAT as specific variant
- `<graph type>` which graph type the operator is intended for
    - `csc`: simple csc representation of a graph
    - `bipartite`: simple csc representation of a bipartite graph
    - `mfg`: message flow graph
- `<"direction">`: for easier overview of which operators we already have, multiple directions are combined and separated through underscores (e.g. `e2n_n2n`)
    - `n2n`: node-to-node (basic aggregation)
    - `e2n`: edge-to-node
    - `e2e`: edge-to-edge
    - `n2s`: node-to-scalar
- `<operator specification>`: some operators define different kinds of "flavors", e.g. the "pre" and the "post" variant of the `hg_basis` operators


## Function Signatures

The following pattern should be used
```
func(output_vector_arg_0, ..., output_vector_arg_n,
     input_vector_arg_0, ..., input_vector_arg_n,
     graph_structure_arg_0, ..., graph_structure_arg_n,
     *args,
     **kwargs,
     cuda_stream=None)
```
- `*args`: arguments necessary for `func` but neither a buffer nor a graph structure
- `**kwargs`: optional arguments or arguments with default values
- `cuda_stream` should be the last argument in a binding if applicable and defaulted to the null stream

Example for RGCN (hg_basis_pre):
```python
def agg_hg_basis_mfg_n2n_pre_bwd(output_gradient,
                                 input_gradient,
                                 input_embedding,
                                 message_flow_graph_hg_csc_int32 graph,
                                 output_weight_gradient=None,
                                 weights_combination=None,
                                 concat_own=False,
                                 norm_by_degree=False,
                                 cuda_stream=None):
```