pCoMole/flow_matching/utils/categorical_sampler.py

# Copyright (c) Meta Platforms, Inc. and affiliates.
# All rights reserved.
#
# This source code is licensed under the CC-by-NC license found in the
# LICENSE file in the root directory of this source tree.

import torch
from torch import Tensor


def categorical(probs: Tensor) -> Tensor:
    r"""Categorical sampler according to weights in the last dimension of ``probs`` using :func:`torch.multinomial`.

    Args:
        probs (Tensor): probabilities.

    Returns:
        Tensor: Samples.
    """

    return torch.multinomial(probs.flatten(0, -2), 1, replacement=True).view(
        *probs.shape[:-1]
    )