from typing import OrderedDict


def stats(arr):
    """
    Return the statistics for an input array of values

    Args:
        arr (np.ndarray)

    Returns:
        OrderedDict

    """
    try:
        return OrderedDict([('min', arr.mean()),
                            ('max', arr.max()),
                            ('mean', arr.mean()),
                            ('std', arr.std())])

    except ValueError:  # Can happen if the input array is empty
        return OrderedDict([('min', None),
                            ('max', None),
                            ('mean', None),
                            ('std', None)])