用Python实现create_target_assigner()函数，用于生成目标分配器

下面是用Python实现create_target_assigner()函数的示例代码：

def create_target_assigner(num_classes, matcher_type='bipartite', weight=None):
    """Create a target assigner function.

    Args:
        num_classes: The number of classes.
        matcher_type: Type of matcher to use for matching groundtruth and
            anchor annotations. Supported options are 'bipartite' and 'per_prediction'.
        weight: The weight to assign to the matched target.

    Returns:
        target_assigner_fn: A function that assigns targets to anchor annotations.

    Raises:
        ValueError: If an invalid matcher_type is provided.
    """

    if matcher_type == 'bipartite':
        def target_assigner_fn(anchor_annotations, groundtruth_annotations):
            """Assigns targets to anchor annotations using bipartite matching.

            Args:
                anchor_annotations: A list of anchor annotations.
                groundtruth_annotations: A list of groundtruth annotations.

            Returns:
                matched_targets: A list of matched targets for anchor annotations.
            """

            # Implementation goes here

        return target_assigner_fn

    elif matcher_type == 'per_prediction':
        def target_assigner_fn(anchor_annotations, groundtruth_annotations):
            """Assigns targets to anchor annotations on a per-prediction basis.

            Args:
                anchor_annotations: A list of anchor annotations.
                groundtruth_annotations: A list of groundtruth annotations.

            Returns:
                matched_targets: A list of matched targets for anchor annotations.
            """

            # Implementation goes here

        return target_assigner_fn

    else:
        raise ValueError("Invalid matcher_type. Supported options are 'bipartite' and 'per_prediction'.")

上述代码中，create_target_assigner()函数接受两个参数：num_classes和matcher_type，以及一个可选的weight参数。num_classes代表类别数量，matcher_type表示匹配器类型，支持'bipartite'和'per_prediction'两种选项。weight参数用于设置匹配目标的权重。

函数会根据matcher_type的值返回不同的目标分配器函数。对于'biaprtite'类型，分配器使用二部图匹配算法对锚点注释和真实注释进行匹配；对于'per_prediction'类型，分配器在每个预测上独立地为锚点注释分配目标。

你可以根据具体需求实现每个目标分配器函数中的代码。