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"""Multibox operations."""
from __future__ import absolute_import as _abs
from . import _make
from ...expr import TupleWrapper

def multibox_prior(data,
                   sizes=(1.0,),
                   ratios=(1.0,),
                   steps=(-1.0, -1.0),
                   offsets=(0.5, 0.5),
                   clip=False):
    """Generate prior(anchor) boxes from data, sizes and ratios.

    Parameters
    ----------
    data : relay.Expr
        The input data tensor.

    sizes : tuple of float, optional
        Tuple of sizes for anchor boxes.

    ratios : tuple of float, optional
        Tuple of ratios for anchor boxes.

    steps : Tuple of float, optional
        Priorbox step across y and x, -1 for auto calculation.

    offsets : tuple of int, optional
        Priorbox center offsets, y and x respectively.

    clip : boolean, optional
        Whether to clip out-of-boundary boxes.

    Returns
    -------
    out : relay.Expr
        3-D tensor with shape [1, h_in * w_in * (num_sizes + num_ratios - 1), 4]
    """
    return _make.multibox_prior(data, sizes, ratios, steps, offsets, clip)


def multibox_transform_loc(cls_prob,
                           loc_pred,
                           anchor,
                           clip=True,
                           threshold=0.01,
                           variances=(0.1, 0.1, 0.2, 0.2)):
    """Location transformation for multibox detection

    Parameters
    ----------
    cls_prob : tvm.relay.Expr
        Class probabilities.

    loc_pred : tvm.relay.Expr
        Location regression predictions.

    anchor : tvm.relay.Expr
        Prior anchor boxes.

    clip : boolean, optional
        Whether to clip out-of-boundary boxes.

    threshold : double, optional
        Threshold to be a positive prediction.

    variances : Tuple of float, optional
        variances to be decoded from box regression output.

    Returns
    -------
    ret : tuple of tvm.relay.Expr
    """
    return TupleWrapper(_make.multibox_transform_loc(cls_prob, loc_pred,
                                                     anchor, clip, threshold,
                                                     variances), 2)
