python/tvm/relay/op/algorithm.py

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"""Classic algorithm operation"""
from __future__ import absolute_import as _abs

from ..expr import Constant, Expr, TupleWrapper
from . import _make
from .dyn import _make as _dyn_make


def sort(data, axis=-1, is_ascend=1):
    """Performs sorting along the given axis and returns data in sorted order.

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

    axis : int, optional
        Axis long which to sort the input tensor.

    is_ascend : boolean, optional
        Whether to sort in ascending or descending order.

    Returns
    -------
    out : relay.Expr
        Tensor with same shape as data.
    """
    return _make.sort(data, axis, is_ascend)


def argsort(data, axis=-1, is_ascend=1, dtype="int32"):
    """Performs sorting along the given axis and returns an array of indices
    having same shape as an input array that index data in sorted order.

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

    valid_count : tvm.te.Tensor
        The number of valid elements to be sorted.

    axis : int, optional
        Axis long which to sort the input tensor.

    is_ascend : boolean, optional
        Whether to sort in ascending or descending order.

    dtype : string, optional
        The data type of the output indices.

    Returns
    -------
    out : relay.Expr
        Tensor with same shape as data.
    """
    return _make.argsort(data, axis, is_ascend, dtype)


def topk(data, k=1, axis=-1, ret_type="both", is_ascend=False, dtype="int32"):
    """Get the top k elements in an input tensor along the given axis.

    ret_type specifies the return type, can be one of ("both", "values", "indices").

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

    k : int or relay.Expr, optional
        Number of top elements to select. Return all elements if k < 1.

    axis : int, optional
        Axis long which to sort the input tensor.

    ret_type: str, optional
        The return type [both, values, indices].
        "both": return both top k data and indices.
        "values": return top k data only.
        "indices": return top k indices only.

    is_ascend : boolean, optional
        Whether to sort in ascending or descending order.

    dtype : string, optional
        The data type of the indices output.

    Returns
    -------
    out : relay.Expr or List[relay.Expr]
        The computed result.
    """
    if isinstance(k, Constant):
        k = k.data.numpy().item()
    if isinstance(k, Expr):
        out = _dyn_make.topk(data, k, axis, ret_type, is_ascend, dtype)
    else:
        out = _make.topk(data, k, axis, ret_type, is_ascend, dtype)
    if ret_type == "both":
        return TupleWrapper(out, 2)
    return out


def searchsorted(sorted_sequence, values, right=False, dtype="int32"):
    """Find indices where elements should be inserted to maintain order.
       If `sorted_sequence` is N-dimensional, the innermost dimension of
       `values` are searched in the corresponding dimension of `sorted_sequence`.

    Parameters
    ----------
    sorted_sequence : relay.Expr
        N-D or 1-D Tensor, containing monotonically increasing sequence
        on the innermost dimension.

    values : relay.Expr
        N-D Tensor containing the search values. When `sorted_sequence` is 1-D,
        the shape of `values` can be arbitrary. Otherwise, ranks of `sorted_sequence`
        and `values` must be the same, and outer N-1 axes must have the same size.

    right : bool, optional
        Controls which index is returned if a value lands exactly on one of sorted values. If
        False, the index of the first suitable location found is given. If true, return the
        last such index. If there is no suitable index, return either 0 or N (where N is the
        size of the innermost dimension).

    dtype : string, optional
        The data type of the output indices.

    Returns
    -------
    indices : relay.Expr
        Tensor with same shape as values, representing the indices of
        elements of `values` if they are inserted in `sorted_sequence`.
    """
    return _make.searchsorted(sorted_sequence, values, right, dtype)