math.py 文件源码

def cummax(x, reverse=False, name=None):
    """Compute the cumulative maximum of the tensor `x` along `axis`. This
    operation is similar to the more classic `cumsum`. Only support 1D Tensor
    for now.

    Args:
    x: A `Tensor`. Must be one of the following types: `float32`, `float64`,
       `int64`, `int32`, `uint8`, `uint16`, `int16`, `int8`, `complex64`,
       `complex128`, `qint8`, `quint8`, `qint32`, `half`.
       axis: A `Tensor` of type `int32` (default: 0).
       reverse: A `bool` (default: False).
       name: A name for the operation (optional).
    Returns:
    A `Tensor`. Has the same type as `x`.
    """
    with ops.name_scope(name, "Cummax", [x]) as name:
        x = ops.convert_to_tensor(x, name="x")
        # Not very optimal: should directly integrate reverse into tf.scan.
        if reverse:
            x = tf.reverse(x, axis=[0])
        # 'Accumlating' maximum: ensure it is always increasing.
        cmax = tf.scan(lambda a, y: tf.maximum(a, y), x,
                       initializer=None, parallel_iterations=1,
                       back_prop=False, swap_memory=False)
        if reverse:
            cmax = tf.reverse(cmax, axis=[0])
        return cmax