MLPY/Lib/site-packages/numpy/lib/arraysetops.py

"""

Set operations for arrays based on sorting.



Notes

-----



For floating point arrays, inaccurate results may appear due to usual round-off

and floating point comparison issues.



Speed could be gained in some operations by an implementation of

`numpy.sort`, that can provide directly the permutation vectors, thus avoiding

calls to `numpy.argsort`.



Original author: Robert Cimrman



"""
import functools

import numpy as np
from numpy.core import overrides


array_function_dispatch = functools.partial(
    overrides.array_function_dispatch, module='numpy')


__all__ = [
    'ediff1d', 'intersect1d', 'setxor1d', 'union1d', 'setdiff1d', 'unique',
    'in1d', 'isin'
    ]


def _ediff1d_dispatcher(ary, to_end=None, to_begin=None):
    return (ary, to_end, to_begin)


@array_function_dispatch(_ediff1d_dispatcher)
def ediff1d(ary, to_end=None, to_begin=None):
    """

    The differences between consecutive elements of an array.



    Parameters

    ----------

    ary : array_like

        If necessary, will be flattened before the differences are taken.

    to_end : array_like, optional

        Number(s) to append at the end of the returned differences.

    to_begin : array_like, optional

        Number(s) to prepend at the beginning of the returned differences.



    Returns

    -------

    ediff1d : ndarray

        The differences. Loosely, this is ``ary.flat[1:] - ary.flat[:-1]``.



    See Also

    --------

    diff, gradient



    Notes

    -----

    When applied to masked arrays, this function drops the mask information

    if the `to_begin` and/or `to_end` parameters are used.



    Examples

    --------

    >>> x = np.array([1, 2, 4, 7, 0])

    >>> np.ediff1d(x)

    array([ 1,  2,  3, -7])



    >>> np.ediff1d(x, to_begin=-99, to_end=np.array([88, 99]))

    array([-99,   1,   2, ...,  -7,  88,  99])



    The returned array is always 1D.



    >>> y = [[1, 2, 4], [1, 6, 24]]

    >>> np.ediff1d(y)

    array([ 1,  2, -3,  5, 18])



    """
    # force a 1d array
    ary = np.asanyarray(ary).ravel()

    # enforce that the dtype of `ary` is used for the output
    dtype_req = ary.dtype

    # fast track default case
    if to_begin is None and to_end is None:
        return ary[1:] - ary[:-1]

    if to_begin is None:
        l_begin = 0
    else:
        to_begin = np.asanyarray(to_begin)
        if not np.can_cast(to_begin, dtype_req, casting="same_kind"):
            raise TypeError("dtype of `to_begin` must be compatible "
                            "with input `ary` under the `same_kind` rule.")

        to_begin = to_begin.ravel()
        l_begin = len(to_begin)

    if to_end is None:
        l_end = 0
    else:
        to_end = np.asanyarray(to_end)
        if not np.can_cast(to_end, dtype_req, casting="same_kind"):
            raise TypeError("dtype of `to_end` must be compatible "
                            "with input `ary` under the `same_kind` rule.")

        to_end = to_end.ravel()
        l_end = len(to_end)

    # do the calculation in place and copy to_begin and to_end
    l_diff = max(len(ary) - 1, 0)
    result = np.empty(l_diff + l_begin + l_end, dtype=ary.dtype)
    result = ary.__array_wrap__(result)
    if l_begin > 0:
        result[:l_begin] = to_begin
    if l_end > 0:
        result[l_begin + l_diff:] = to_end
    np.subtract(ary[1:], ary[:-1], result[l_begin:l_begin + l_diff])
    return result


def _unpack_tuple(x):
    """ Unpacks one-element tuples for use as return values """
    if len(x) == 1:
        return x[0]
    else:
        return x


def _unique_dispatcher(ar, return_index=None, return_inverse=None,

                       return_counts=None, axis=None):
    return (ar,)


@array_function_dispatch(_unique_dispatcher)
def unique(ar, return_index=False, return_inverse=False,

           return_counts=False, axis=None):
    """

    Find the unique elements of an array.



    Returns the sorted unique elements of an array. There are three optional

    outputs in addition to the unique elements:



    * the indices of the input array that give the unique values

    * the indices of the unique array that reconstruct the input array

    * the number of times each unique value comes up in the input array



    Parameters

    ----------

    ar : array_like

        Input array. Unless `axis` is specified, this will be flattened if it

        is not already 1-D.

    return_index : bool, optional

        If True, also return the indices of `ar` (along the specified axis,

        if provided, or in the flattened array) that result in the unique array.

    return_inverse : bool, optional

        If True, also return the indices of the unique array (for the specified

        axis, if provided) that can be used to reconstruct `ar`.

    return_counts : bool, optional

        If True, also return the number of times each unique item appears

        in `ar`.



        .. versionadded:: 1.9.0



    axis : int or None, optional

        The axis to operate on. If None, `ar` will be flattened. If an integer,

        the subarrays indexed by the given axis will be flattened and treated

        as the elements of a 1-D array with the dimension of the given axis,

        see the notes for more details.  Object arrays or structured arrays

        that contain objects are not supported if the `axis` kwarg is used. The

        default is None.



        .. versionadded:: 1.13.0



    Returns

    -------

    unique : ndarray

        The sorted unique values.

    unique_indices : ndarray, optional

        The indices of the first occurrences of the unique values in the

        original array. Only provided if `return_index` is True.

    unique_inverse : ndarray, optional

        The indices to reconstruct the original array from the

        unique array. Only provided if `return_inverse` is True.

    unique_counts : ndarray, optional

        The number of times each of the unique values comes up in the

        original array. Only provided if `return_counts` is True.



        .. versionadded:: 1.9.0



    See Also

    --------

    numpy.lib.arraysetops : Module with a number of other functions for

                            performing set operations on arrays.

    repeat : Repeat elements of an array.



    Notes

    -----

    When an axis is specified the subarrays indexed by the axis are sorted.

    This is done by making the specified axis the first dimension of the array

    (move the axis to the first dimension to keep the order of the other axes)

    and then flattening the subarrays in C order. The flattened subarrays are

    then viewed as a structured type with each element given a label, with the

    effect that we end up with a 1-D array of structured types that can be

    treated in the same way as any other 1-D array. The result is that the

    flattened subarrays are sorted in lexicographic order starting with the

    first element.



    .. versionchanged: NumPy 1.21

        If nan values are in the input array, a single nan is put

        to the end of the sorted unique values.



        Also for complex arrays all NaN values are considered equivalent

        (no matter whether the NaN is in the real or imaginary part).

        As the representant for the returned array the smallest one in the

        lexicographical order is chosen - see np.sort for how the lexicographical

        order is defined for complex arrays.



    Examples

    --------

    >>> np.unique([1, 1, 2, 2, 3, 3])

    array([1, 2, 3])

    >>> a = np.array([[1, 1], [2, 3]])

    >>> np.unique(a)

    array([1, 2, 3])



    Return the unique rows of a 2D array



    >>> a = np.array([[1, 0, 0], [1, 0, 0], [2, 3, 4]])

    >>> np.unique(a, axis=0)

    array([[1, 0, 0], [2, 3, 4]])



    Return the indices of the original array that give the unique values:



    >>> a = np.array(['a', 'b', 'b', 'c', 'a'])

    >>> u, indices = np.unique(a, return_index=True)

    >>> u

    array(['a', 'b', 'c'], dtype='<U1')

    >>> indices

    array([0, 1, 3])

    >>> a[indices]

    array(['a', 'b', 'c'], dtype='<U1')



    Reconstruct the input array from the unique values and inverse:



    >>> a = np.array([1, 2, 6, 4, 2, 3, 2])

    >>> u, indices = np.unique(a, return_inverse=True)

    >>> u

    array([1, 2, 3, 4, 6])

    >>> indices

    array([0, 1, 4, 3, 1, 2, 1])

    >>> u[indices]

    array([1, 2, 6, 4, 2, 3, 2])



    Reconstruct the input values from the unique values and counts:



    >>> a = np.array([1, 2, 6, 4, 2, 3, 2])

    >>> values, counts = np.unique(a, return_counts=True)

    >>> values

    array([1, 2, 3, 4, 6])

    >>> counts

    array([1, 3, 1, 1, 1])

    >>> np.repeat(values, counts)

    array([1, 2, 2, 2, 3, 4, 6])    # original order not preserved



    """
    ar = np.asanyarray(ar)
    if axis is None:
        ret = _unique1d(ar, return_index, return_inverse, return_counts)
        return _unpack_tuple(ret)

    # axis was specified and not None
    try:
        ar = np.moveaxis(ar, axis, 0)
    except np.AxisError:
        # this removes the "axis1" or "axis2" prefix from the error message
        raise np.AxisError(axis, ar.ndim) from None

    # Must reshape to a contiguous 2D array for this to work...
    orig_shape, orig_dtype = ar.shape, ar.dtype
    ar = ar.reshape(orig_shape[0], np.prod(orig_shape[1:], dtype=np.intp))
    ar = np.ascontiguousarray(ar)
    dtype = [('f{i}'.format(i=i), ar.dtype) for i in range(ar.shape[1])]

    # At this point, `ar` has shape `(n, m)`, and `dtype` is a structured
    # data type with `m` fields where each field has the data type of `ar`.
    # In the following, we create the array `consolidated`, which has
    # shape `(n,)` with data type `dtype`.
    try:
        if ar.shape[1] > 0:
            consolidated = ar.view(dtype)
        else:
            # If ar.shape[1] == 0, then dtype will be `np.dtype([])`, which is
            # a data type with itemsize 0, and the call `ar.view(dtype)` will
            # fail.  Instead, we'll use `np.empty` to explicitly create the
            # array with shape `(len(ar),)`.  Because `dtype` in this case has
            # itemsize 0, the total size of the result is still 0 bytes.
            consolidated = np.empty(len(ar), dtype=dtype)
    except TypeError as e:
        # There's no good way to do this for object arrays, etc...
        msg = 'The axis argument to unique is not supported for dtype {dt}'
        raise TypeError(msg.format(dt=ar.dtype)) from e

    def reshape_uniq(uniq):
        n = len(uniq)
        uniq = uniq.view(orig_dtype)
        uniq = uniq.reshape(n, *orig_shape[1:])
        uniq = np.moveaxis(uniq, 0, axis)
        return uniq

    output = _unique1d(consolidated, return_index,
                       return_inverse, return_counts)
    output = (reshape_uniq(output[0]),) + output[1:]
    return _unpack_tuple(output)


def _unique1d(ar, return_index=False, return_inverse=False,

              return_counts=False):
    """

    Find the unique elements of an array, ignoring shape.

    """
    ar = np.asanyarray(ar).flatten()

    optional_indices = return_index or return_inverse

    if optional_indices:
        perm = ar.argsort(kind='mergesort' if return_index else 'quicksort')
        aux = ar[perm]
    else:
        ar.sort()
        aux = ar
    mask = np.empty(aux.shape, dtype=np.bool_)
    mask[:1] = True
    if aux.shape[0] > 0 and aux.dtype.kind in "cfmM" and np.isnan(aux[-1]):
        if aux.dtype.kind == "c":  # for complex all NaNs are considered equivalent
            aux_firstnan = np.searchsorted(np.isnan(aux), True, side='left')
        else:
            aux_firstnan = np.searchsorted(aux, aux[-1], side='left')
        if aux_firstnan > 0:
            mask[1:aux_firstnan] = (
                aux[1:aux_firstnan] != aux[:aux_firstnan - 1])
        mask[aux_firstnan] = True
        mask[aux_firstnan + 1:] = False
    else:
        mask[1:] = aux[1:] != aux[:-1]

    ret = (aux[mask],)
    if return_index:
        ret += (perm[mask],)
    if return_inverse:
        imask = np.cumsum(mask) - 1
        inv_idx = np.empty(mask.shape, dtype=np.intp)
        inv_idx[perm] = imask
        ret += (inv_idx,)
    if return_counts:
        idx = np.concatenate(np.nonzero(mask) + ([mask.size],))
        ret += (np.diff(idx),)
    return ret


def _intersect1d_dispatcher(

        ar1, ar2, assume_unique=None, return_indices=None):
    return (ar1, ar2)


@array_function_dispatch(_intersect1d_dispatcher)
def intersect1d(ar1, ar2, assume_unique=False, return_indices=False):
    """

    Find the intersection of two arrays.



    Return the sorted, unique values that are in both of the input arrays.



    Parameters

    ----------

    ar1, ar2 : array_like

        Input arrays. Will be flattened if not already 1D.

    assume_unique : bool

        If True, the input arrays are both assumed to be unique, which

        can speed up the calculation.  If True but ``ar1`` or ``ar2`` are not

        unique, incorrect results and out-of-bounds indices could result.

        Default is False.

    return_indices : bool

        If True, the indices which correspond to the intersection of the two

        arrays are returned. The first instance of a value is used if there are

        multiple. Default is False.



        .. versionadded:: 1.15.0



    Returns

    -------

    intersect1d : ndarray

        Sorted 1D array of common and unique elements.

    comm1 : ndarray

        The indices of the first occurrences of the common values in `ar1`.

        Only provided if `return_indices` is True.

    comm2 : ndarray

        The indices of the first occurrences of the common values in `ar2`.

        Only provided if `return_indices` is True.





    See Also

    --------

    numpy.lib.arraysetops : Module with a number of other functions for

                            performing set operations on arrays.



    Examples

    --------

    >>> np.intersect1d([1, 3, 4, 3], [3, 1, 2, 1])

    array([1, 3])



    To intersect more than two arrays, use functools.reduce:



    >>> from functools import reduce

    >>> reduce(np.intersect1d, ([1, 3, 4, 3], [3, 1, 2, 1], [6, 3, 4, 2]))

    array([3])



    To return the indices of the values common to the input arrays

    along with the intersected values:



    >>> x = np.array([1, 1, 2, 3, 4])

    >>> y = np.array([2, 1, 4, 6])

    >>> xy, x_ind, y_ind = np.intersect1d(x, y, return_indices=True)

    >>> x_ind, y_ind

    (array([0, 2, 4]), array([1, 0, 2]))

    >>> xy, x[x_ind], y[y_ind]

    (array([1, 2, 4]), array([1, 2, 4]), array([1, 2, 4]))



    """
    ar1 = np.asanyarray(ar1)
    ar2 = np.asanyarray(ar2)

    if not assume_unique:
        if return_indices:
            ar1, ind1 = unique(ar1, return_index=True)
            ar2, ind2 = unique(ar2, return_index=True)
        else:
            ar1 = unique(ar1)
            ar2 = unique(ar2)
    else:
        ar1 = ar1.ravel()
        ar2 = ar2.ravel()

    aux = np.concatenate((ar1, ar2))
    if return_indices:
        aux_sort_indices = np.argsort(aux, kind='mergesort')
        aux = aux[aux_sort_indices]
    else:
        aux.sort()

    mask = aux[1:] == aux[:-1]
    int1d = aux[:-1][mask]

    if return_indices:
        ar1_indices = aux_sort_indices[:-1][mask]
        ar2_indices = aux_sort_indices[1:][mask] - ar1.size
        if not assume_unique:
            ar1_indices = ind1[ar1_indices]
            ar2_indices = ind2[ar2_indices]

        return int1d, ar1_indices, ar2_indices
    else:
        return int1d


def _setxor1d_dispatcher(ar1, ar2, assume_unique=None):
    return (ar1, ar2)


@array_function_dispatch(_setxor1d_dispatcher)
def setxor1d(ar1, ar2, assume_unique=False):
    """

    Find the set exclusive-or of two arrays.



    Return the sorted, unique values that are in only one (not both) of the

    input arrays.



    Parameters

    ----------

    ar1, ar2 : array_like

        Input arrays.

    assume_unique : bool

        If True, the input arrays are both assumed to be unique, which

        can speed up the calculation.  Default is False.



    Returns

    -------

    setxor1d : ndarray

        Sorted 1D array of unique values that are in only one of the input

        arrays.



    Examples

    --------

    >>> a = np.array([1, 2, 3, 2, 4])

    >>> b = np.array([2, 3, 5, 7, 5])

    >>> np.setxor1d(a,b)

    array([1, 4, 5, 7])



    """
    if not assume_unique:
        ar1 = unique(ar1)
        ar2 = unique(ar2)

    aux = np.concatenate((ar1, ar2))
    if aux.size == 0:
        return aux

    aux.sort()
    flag = np.concatenate(([True], aux[1:] != aux[:-1], [True]))
    return aux[flag[1:] & flag[:-1]]


def _in1d_dispatcher(ar1, ar2, assume_unique=None, invert=None):
    return (ar1, ar2)


@array_function_dispatch(_in1d_dispatcher)
def in1d(ar1, ar2, assume_unique=False, invert=False):
    """

    Test whether each element of a 1-D array is also present in a second array.



    Returns a boolean array the same length as `ar1` that is True

    where an element of `ar1` is in `ar2` and False otherwise.



    We recommend using :func:`isin` instead of `in1d` for new code.



    Parameters

    ----------

    ar1 : (M,) array_like

        Input array.

    ar2 : array_like

        The values against which to test each value of `ar1`.

    assume_unique : bool, optional

        If True, the input arrays are both assumed to be unique, which

        can speed up the calculation.  Default is False.

    invert : bool, optional

        If True, the values in the returned array are inverted (that is,

        False where an element of `ar1` is in `ar2` and True otherwise).

        Default is False. ``np.in1d(a, b, invert=True)`` is equivalent

        to (but is faster than) ``np.invert(in1d(a, b))``.



        .. versionadded:: 1.8.0



    Returns

    -------

    in1d : (M,) ndarray, bool

        The values `ar1[in1d]` are in `ar2`.



    See Also

    --------

    isin                  : Version of this function that preserves the

                            shape of ar1.

    numpy.lib.arraysetops : Module with a number of other functions for

                            performing set operations on arrays.



    Notes

    -----

    `in1d` can be considered as an element-wise function version of the

    python keyword `in`, for 1-D sequences. ``in1d(a, b)`` is roughly

    equivalent to ``np.array([item in b for item in a])``.

    However, this idea fails if `ar2` is a set, or similar (non-sequence)

    container:  As ``ar2`` is converted to an array, in those cases

    ``asarray(ar2)`` is an object array rather than the expected array of

    contained values.



    .. versionadded:: 1.4.0



    Examples

    --------

    >>> test = np.array([0, 1, 2, 5, 0])

    >>> states = [0, 2]

    >>> mask = np.in1d(test, states)

    >>> mask

    array([ True, False,  True, False,  True])

    >>> test[mask]

    array([0, 2, 0])

    >>> mask = np.in1d(test, states, invert=True)

    >>> mask

    array([False,  True, False,  True, False])

    >>> test[mask]

    array([1, 5])

    """
    # Ravel both arrays, behavior for the first array could be different
    ar1 = np.asarray(ar1).ravel()
    ar2 = np.asarray(ar2).ravel()

    # Ensure that iteration through object arrays yields size-1 arrays
    if ar2.dtype == object:
        ar2 = ar2.reshape(-1, 1)

    # Check if one of the arrays may contain arbitrary objects
    contains_object = ar1.dtype.hasobject or ar2.dtype.hasobject

    # This code is run when
    # a) the first condition is true, making the code significantly faster
    # b) the second condition is true (i.e. `ar1` or `ar2` may contain
    #    arbitrary objects), since then sorting is not guaranteed to work
    if len(ar2) < 10 * len(ar1) ** 0.145 or contains_object:
        if invert:
            mask = np.ones(len(ar1), dtype=bool)
            for a in ar2:
                mask &= (ar1 != a)
        else:
            mask = np.zeros(len(ar1), dtype=bool)
            for a in ar2:
                mask |= (ar1 == a)
        return mask

    # Otherwise use sorting
    if not assume_unique:
        ar1, rev_idx = np.unique(ar1, return_inverse=True)
        ar2 = np.unique(ar2)

    ar = np.concatenate((ar1, ar2))
    # We need this to be a stable sort, so always use 'mergesort'
    # here. The values from the first array should always come before
    # the values from the second array.
    order = ar.argsort(kind='mergesort')
    sar = ar[order]
    if invert:
        bool_ar = (sar[1:] != sar[:-1])
    else:
        bool_ar = (sar[1:] == sar[:-1])
    flag = np.concatenate((bool_ar, [invert]))
    ret = np.empty(ar.shape, dtype=bool)
    ret[order] = flag

    if assume_unique:
        return ret[:len(ar1)]
    else:
        return ret[rev_idx]


def _isin_dispatcher(element, test_elements, assume_unique=None, invert=None):
    return (element, test_elements)


@array_function_dispatch(_isin_dispatcher)
def isin(element, test_elements, assume_unique=False, invert=False):
    """

    Calculates `element in test_elements`, broadcasting over `element` only.

    Returns a boolean array of the same shape as `element` that is True

    where an element of `element` is in `test_elements` and False otherwise.



    Parameters

    ----------

    element : array_like

        Input array.

    test_elements : array_like

        The values against which to test each value of `element`.

        This argument is flattened if it is an array or array_like.

        See notes for behavior with non-array-like parameters.

    assume_unique : bool, optional

        If True, the input arrays are both assumed to be unique, which

        can speed up the calculation.  Default is False.

    invert : bool, optional

        If True, the values in the returned array are inverted, as if

        calculating `element not in test_elements`. Default is False.

        ``np.isin(a, b, invert=True)`` is equivalent to (but faster

        than) ``np.invert(np.isin(a, b))``.



    Returns

    -------

    isin : ndarray, bool

        Has the same shape as `element`. The values `element[isin]`

        are in `test_elements`.



    See Also

    --------

    in1d                  : Flattened version of this function.

    numpy.lib.arraysetops : Module with a number of other functions for

                            performing set operations on arrays.



    Notes

    -----



    `isin` is an element-wise function version of the python keyword `in`.

    ``isin(a, b)`` is roughly equivalent to

    ``np.array([item in b for item in a])`` if `a` and `b` are 1-D sequences.



    `element` and `test_elements` are converted to arrays if they are not

    already. If `test_elements` is a set (or other non-sequence collection)

    it will be converted to an object array with one element, rather than an

    array of the values contained in `test_elements`. This is a consequence

    of the `array` constructor's way of handling non-sequence collections.

    Converting the set to a list usually gives the desired behavior.



    .. versionadded:: 1.13.0



    Examples

    --------

    >>> element = 2*np.arange(4).reshape((2, 2))

    >>> element

    array([[0, 2],

           [4, 6]])

    >>> test_elements = [1, 2, 4, 8]

    >>> mask = np.isin(element, test_elements)

    >>> mask

    array([[False,  True],

           [ True, False]])

    >>> element[mask]

    array([2, 4])



    The indices of the matched values can be obtained with `nonzero`:



    >>> np.nonzero(mask)

    (array([0, 1]), array([1, 0]))



    The test can also be inverted:



    >>> mask = np.isin(element, test_elements, invert=True)

    >>> mask

    array([[ True, False],

           [False,  True]])

    >>> element[mask]

    array([0, 6])



    Because of how `array` handles sets, the following does not

    work as expected:



    >>> test_set = {1, 2, 4, 8}

    >>> np.isin(element, test_set)

    array([[False, False],

           [False, False]])



    Casting the set to a list gives the expected result:



    >>> np.isin(element, list(test_set))

    array([[False,  True],

           [ True, False]])

    """
    element = np.asarray(element)
    return in1d(element, test_elements, assume_unique=assume_unique,
                invert=invert).reshape(element.shape)


def _union1d_dispatcher(ar1, ar2):
    return (ar1, ar2)


@array_function_dispatch(_union1d_dispatcher)
def union1d(ar1, ar2):
    """

    Find the union of two arrays.



    Return the unique, sorted array of values that are in either of the two

    input arrays.



    Parameters

    ----------

    ar1, ar2 : array_like

        Input arrays. They are flattened if they are not already 1D.



    Returns

    -------

    union1d : ndarray

        Unique, sorted union of the input arrays.



    See Also

    --------

    numpy.lib.arraysetops : Module with a number of other functions for

                            performing set operations on arrays.



    Examples

    --------

    >>> np.union1d([-1, 0, 1], [-2, 0, 2])

    array([-2, -1,  0,  1,  2])



    To find the union of more than two arrays, use functools.reduce:



    >>> from functools import reduce

    >>> reduce(np.union1d, ([1, 3, 4, 3], [3, 1, 2, 1], [6, 3, 4, 2]))

    array([1, 2, 3, 4, 6])

    """
    return unique(np.concatenate((ar1, ar2), axis=None))


def _setdiff1d_dispatcher(ar1, ar2, assume_unique=None):
    return (ar1, ar2)


@array_function_dispatch(_setdiff1d_dispatcher)
def setdiff1d(ar1, ar2, assume_unique=False):
    """

    Find the set difference of two arrays.



    Return the unique values in `ar1` that are not in `ar2`.



    Parameters

    ----------

    ar1 : array_like

        Input array.

    ar2 : array_like

        Input comparison array.

    assume_unique : bool

        If True, the input arrays are both assumed to be unique, which

        can speed up the calculation.  Default is False.



    Returns

    -------

    setdiff1d : ndarray

        1D array of values in `ar1` that are not in `ar2`. The result

        is sorted when `assume_unique=False`, but otherwise only sorted

        if the input is sorted.



    See Also

    --------

    numpy.lib.arraysetops : Module with a number of other functions for

                            performing set operations on arrays.



    Examples

    --------

    >>> a = np.array([1, 2, 3, 2, 4, 1])

    >>> b = np.array([3, 4, 5, 6])

    >>> np.setdiff1d(a, b)

    array([1, 2])



    """
    if assume_unique:
        ar1 = np.asarray(ar1).ravel()
    else:
        ar1 = unique(ar1)
        ar2 = unique(ar2)
    return ar1[in1d(ar1, ar2, assume_unique=True, invert=True)]