Python numpy.broadcast() Examples

def check_power_divergence(self, f_obs, f_exp, ddof, axis, lambda_,
                               expected_stat):
        f_obs = np.asarray(f_obs)
        if axis is None:
            num_obs = f_obs.size
        else:
            b = np.broadcast(f_obs, f_exp)
            num_obs = b.shape[axis]
        stat, p = stats.power_divergence(f_obs=f_obs, f_exp=f_exp, ddof=ddof,
                                         axis=axis, lambda_=lambda_)
        assert_allclose(stat, expected_stat)

        if lambda_ == 1 or lambda_ == "pearson":
            # Also test stats.chisquare.
            stat, p = stats.chisquare(f_obs=f_obs, f_exp=f_exp, ddof=ddof,
                                      axis=axis)
            assert_allclose(stat, expected_stat)

        ddof = np.asarray(ddof)
        expected_p = stats.chisqprob(expected_stat, num_obs - 1 - ddof)
        assert_allclose(p, expected_p) 

def broadcast_shape(shp1, shp2):
    """Broadcast the shape of those arrays

    Parameters
    ----------
    shp1 : tuple
        shape of array 1
    shp2 : tuple
        shape of array 2

    Returns
    -------
    tuple
        shape resulting from broadcasting two arrays using numpy rules

    Raises
    ------
    ValueError
        Arrays cannot be broadcasted
    """
    try:
        return np.broadcast(np.empty(shp1), np.empty(shp2)).shape
    except ValueError:
        raise ValueError("Arrays cannot be broadcasted - %s and %s " % (str(shp1), str(shp2))) 

def _broadcast_shape(*args):
    """Returns the shape of the arrays that would result from broadcasting the
    supplied arrays against each other.
    """
    if not args:
        return ()
    # use the old-iterator because np.nditer does not handle size 0 arrays
    # consistently
    b = np.broadcast(*args[:32])
    # unfortunately, it cannot handle 32 or more arguments directly
    for pos in range(32, len(args), 31):
        # ironically, np.broadcast does not properly handle np.broadcast
        # objects (it treats them as scalars)
        # use broadcasting to avoid allocating the full array
        b = broadcast_to(0, b.shape)
        b = np.broadcast(b, *args[pos:(pos + 31)])
    return b.shape 

def _broadcast_to(array, shape, subok, readonly):
    shape = tuple(shape) if np.iterable(shape) else (shape,)
    array = np.array(array, copy=False, subok=subok)
    if not shape and array.shape:
        raise ValueError('cannot broadcast a non-scalar to a scalar array')
    if any(size < 0 for size in shape):
        raise ValueError('all elements of broadcast shape must be non-'
                         'negative')
    needs_writeable = not readonly and array.flags.writeable
    extras = ['reduce_ok'] if needs_writeable else []
    op_flag = 'readwrite' if needs_writeable else 'readonly'
    it = np.nditer(
        (array,), flags=['multi_index', 'refs_ok', 'zerosize_ok'] + extras,
        op_flags=[op_flag], itershape=shape, order='C')
    with it:
        # never really has writebackifcopy semantics
        broadcast = it.itviews[0]
    result = _maybe_view_as_subclass(array, broadcast)
    if needs_writeable and not result.flags.writeable:
        result.flags.writeable = True
    return result 

def _broadcast_shape(*args):
    """Returns the shape of the arrays that would result from broadcasting the
    supplied arrays against each other.
    """
    if not args:
        return ()
    # use the old-iterator because np.nditer does not handle size 0 arrays
    # consistently
    b = np.broadcast(*args[:32])
    # unfortunately, it cannot handle 32 or more arguments directly
    for pos in range(32, len(args), 31):
        # ironically, np.broadcast does not properly handle np.broadcast
        # objects (it treats them as scalars)
        # use broadcasting to avoid allocating the full array
        b = broadcast_to(0, b.shape)
        b = np.broadcast(b, *args[pos:(pos + 31)])
    return b.shape 

def _broadcast_to(array, shape, subok, readonly):
    shape = tuple(shape) if np.iterable(shape) else (shape,)
    array = np.array(array, copy=False, subok=subok)
    if not shape and array.shape:
        raise ValueError('cannot broadcast a non-scalar to a scalar array')
    if any(size < 0 for size in shape):
        raise ValueError('all elements of broadcast shape must be non-'
                         'negative')
    needs_writeable = not readonly and array.flags.writeable
    extras = ['reduce_ok'] if needs_writeable else []
    op_flag = 'readwrite' if needs_writeable else 'readonly'
    it = np.nditer(
        (array,), flags=['multi_index', 'refs_ok', 'zerosize_ok'] + extras,
        op_flags=[op_flag], itershape=shape, order='C')
    with it:
        # never really has writebackifcopy semantics
        broadcast = it.itviews[0]
    result = _maybe_view_as_subclass(array, broadcast)
    if needs_writeable and not result.flags.writeable:
        result.flags.writeable = True
    return result 

def _broadcast_to(array, shape, subok, readonly):
    shape = tuple(shape) if np.iterable(shape) else (shape,)
    array = np.array(array, copy=False, subok=subok)
    if not shape and array.shape:
        raise ValueError('cannot broadcast a non-scalar to a scalar array')
    if any(size < 0 for size in shape):
        raise ValueError('all elements of broadcast shape must be non-'
                         'negative')
    needs_writeable = not readonly and array.flags.writeable
    extras = ['reduce_ok'] if needs_writeable else []
    op_flag = 'readwrite' if needs_writeable else 'readonly'
    it = np.nditer(
        (array,), flags=['multi_index', 'refs_ok', 'zerosize_ok'] + extras,
        op_flags=[op_flag], itershape=shape, order='C')
    with it:
        # never really has writebackifcopy semantics
        broadcast = it.itviews[0]
    result = _maybe_view_as_subclass(array, broadcast)
    if needs_writeable and not result.flags.writeable:
        result.flags.writeable = True
    return result 

def _broadcast_to(array, shape, subok, readonly):
    shape = tuple(shape) if np.iterable(shape) else (shape,)
    array = np.array(array, copy=False, subok=subok)
    if not shape and array.shape:
        raise ValueError('cannot broadcast a non-scalar to a scalar array')
    if any(size < 0 for size in shape):
        raise ValueError('all elements of broadcast shape must be non-'
                         'negative')
    needs_writeable = not readonly and array.flags.writeable
    extras = ['reduce_ok'] if needs_writeable else []
    op_flag = 'readwrite' if needs_writeable else 'readonly'
    it = np.nditer(
        (array,), flags=['multi_index', 'refs_ok', 'zerosize_ok'] + extras,
        op_flags=[op_flag], itershape=shape, order='C')
    with it:
        # never really has writebackifcopy semantics
        broadcast = it.itviews[0]
    result = _maybe_view_as_subclass(array, broadcast)
    if needs_writeable and not result.flags.writeable:
        result.flags.writeable = True
    return result 

def _broadcast_to(array, shape, subok, readonly):
    shape = tuple(shape) if np.iterable(shape) else (shape,)
    array = np.array(array, copy=False, subok=subok)
    if not shape and array.shape:
        raise ValueError('cannot broadcast a non-scalar to a scalar array')
    if any(size < 0 for size in shape):
        raise ValueError('all elements of broadcast shape must be non-'
                         'negative')
    needs_writeable = not readonly and array.flags.writeable
    extras = ['reduce_ok'] if needs_writeable else []
    op_flag = 'readwrite' if needs_writeable else 'readonly'
    broadcast = np.nditer(
        (array,), flags=['multi_index', 'refs_ok', 'zerosize_ok'] + extras,
        op_flags=[op_flag], itershape=shape, order='C').itviews[0]
    result = _maybe_view_as_subclass(array, broadcast)
    if needs_writeable and not result.flags.writeable:
        result.flags.writeable = True
    return result 

def _broadcast_to(array, shape, subok, readonly):
    shape = tuple(shape) if np.iterable(shape) else (shape,)
    array = np.array(array, copy=False, subok=subok)
    if not shape and array.shape:
        raise ValueError('cannot broadcast a non-scalar to a scalar array')
    if any(size < 0 for size in shape):
        raise ValueError('all elements of broadcast shape must be non-'
                         'negative')
    needs_writeable = not readonly and array.flags.writeable
    extras = ['reduce_ok'] if needs_writeable else []
    op_flag = 'readwrite' if needs_writeable else 'readonly'
    broadcast = np.nditer(
        (array,), flags=['multi_index', 'refs_ok', 'zerosize_ok'] + extras,
        op_flags=[op_flag], itershape=shape, order='C').itviews[0]
    result = _maybe_view_as_subclass(array, broadcast)
    if needs_writeable and not result.flags.writeable:
        result.flags.writeable = True
    return result 

def _broadcast_shape(*args):
    """Returns the shape of the ararys that would result from broadcasting the
    supplied arrays against each other.
    """
    if not args:
        raise ValueError('must provide at least one argument')
    # use the old-iterator because np.nditer does not handle size 0 arrays
    # consistently
    b = np.broadcast(*args[:32])
    # unfortunately, it cannot handle 32 or more arguments directly
    for pos in range(32, len(args), 31):
        # ironically, np.broadcast does not properly handle np.broadcast
        # objects (it treats them as scalars)
        # use broadcasting to avoid allocating the full array
        b = broadcast_to(0, b.shape)
        b = np.broadcast(b, *args[pos:(pos + 31)])
    return b.shape 

def expect_broadcast_shapes(*shape_types):
    """Checks if shapes can be broadcasted together.

    Args:
        shapes_types: Type-checked shapes of the arrays to broadcast.

    """
    shapes = [eval(s) for s in shape_types]
    error = None
    try:
        # simulate the shape calculation using zero-sized arrays
        numpy.broadcast(*[numpy.empty(s + (0,)) for s in shapes])
    except ValueError:
        msgs = ['cannot broadcast inputs of the following shapes:']
        for shape_type, shape in six.moves.zip(shape_types, shapes):
            msgs.append('{} = {}'.format(shape_type, shape))
        error = InvalidType('', '', msg='\n'.join(msgs))
    if error is not None:
        raise error 

def _broadcast_to(array, shape, subok, readonly):
    shape = tuple(shape) if np.iterable(shape) else (shape,)
    array = np.array(array, copy=False, subok=subok)
    if not shape and array.shape:
        raise ValueError('cannot broadcast a non-scalar to a scalar array')
    if any(size < 0 for size in shape):
        raise ValueError('all elements of broadcast shape must be non-'
                         'negative')
    needs_writeable = not readonly and array.flags.writeable
    extras = ['reduce_ok'] if needs_writeable else []
    op_flag = 'readwrite' if needs_writeable else 'readonly'
    broadcast = np.nditer(
        (array,), flags=['multi_index', 'refs_ok', 'zerosize_ok'] + extras,
        op_flags=[op_flag], itershape=shape, order='C').itviews[0]
    result = _maybe_view_as_subclass(array, broadcast)
    if needs_writeable and not result.flags.writeable:
        result.flags.writeable = True
    return result 

def _broadcast_shape(*args):
    """Returns the shape of the arrays that would result from broadcasting the
    supplied arrays against each other.
    """
    if not args:
        return ()
    # use the old-iterator because np.nditer does not handle size 0 arrays
    # consistently
    b = np.broadcast(*args[:32])
    # unfortunately, it cannot handle 32 or more arguments directly
    for pos in range(32, len(args), 31):
        # ironically, np.broadcast does not properly handle np.broadcast
        # objects (it treats them as scalars)
        # use broadcasting to avoid allocating the full array
        b = broadcast_to(0, b.shape)
        b = np.broadcast(b, *args[pos:(pos + 31)])
    return b.shape 

def _broadcast_shape(*args):
    """Returns the shape of the arrays that would result from broadcasting the
    supplied arrays against each other.
    """
    if not args:
        return ()
    # use the old-iterator because np.nditer does not handle size 0 arrays
    # consistently
    b = np.broadcast(*args[:32])
    # unfortunately, it cannot handle 32 or more arguments directly
    for pos in range(32, len(args), 31):
        # ironically, np.broadcast does not properly handle np.broadcast
        # objects (it treats them as scalars)
        # use broadcasting to avoid allocating the full array
        b = broadcast_to(0, b.shape)
        b = np.broadcast(b, *args[pos:(pos + 31)])
    return b.shape 

def broadcast_shape(*shapes, **kwargs):
    """
    Similar to ``np.broadcast()`` but for shapes.
    Equivalent to ``np.broadcast(*map(np.empty, shapes)).shape``.
    :param tuple shapes: shapes of tensors.
    :param bool strict: whether to use extend-but-not-resize broadcasting.
    :returns: broadcasted shape
    :rtype: tuple
    :raises: ValueError
    """
    strict = kwargs.pop('strict', False)
    reversed_shape = []
    for shape in shapes:
        for i, size in enumerate(reversed(shape)):
            if i >= len(reversed_shape):
                reversed_shape.append(size)
            elif reversed_shape[i] == 1 and not strict:
                reversed_shape[i] = size
            elif reversed_shape[i] != size and (size != 1 or strict):
                raise ValueError('shape mismatch: objects cannot be broadcast to a single shape: {}'.format(
                    ' vs '.join(map(str, shapes))))
    return tuple(reversed(reversed_shape)) 

def _broadcast_shape(*args):
    """Returns the shape of the arrays that would result from broadcasting the
    supplied arrays against each other.
    """
    if not args:
        return ()
    # use the old-iterator because np.nditer does not handle size 0 arrays
    # consistently
    b = np.broadcast(*args[:32])
    # unfortunately, it cannot handle 32 or more arguments directly
    for pos in range(32, len(args), 31):
        # ironically, np.broadcast does not properly handle np.broadcast
        # objects (it treats them as scalars)
        # use broadcasting to avoid allocating the full array
        b = broadcast_to(0, b.shape)
        b = np.broadcast(b, *args[pos:(pos + 31)])
    return b.shape 

def broadcastable(*names):
    """returns a function - this function takes a dict of args
    (should be used in _all validator)
    asserts that every array in that list is broadcastable
    """
    # todo - do we check whether these are numpy objs first?
    # cause you can write numpy funcs on lists sometimes
    import numpy as np

    def _broadcastable(all_args):
        arrs = [all_args[x] for x in names]
        try:
            np.broadcast(*arrs)
        except ValueError:
            raise ValidationError(
                "Cannot broadcast %s with shapes %s", names,
                [getattr(x, 'shape', 'no shape') for x in arrs])
    return _broadcastable 

def _broadcast_to(array, shape, subok, readonly):
    shape = tuple(shape) if np.iterable(shape) else (shape,)
    array = np.array(array, copy=False, subok=subok)
    if not shape and array.shape:
        raise ValueError('cannot broadcast a non-scalar to a scalar array')
    if any(size < 0 for size in shape):
        raise ValueError('all elements of broadcast shape must be non-'
                         'negative')
    needs_writeable = not readonly and array.flags.writeable
    extras = ['reduce_ok'] if needs_writeable else []
    op_flag = 'readwrite' if needs_writeable else 'readonly'
    it = np.nditer(
        (array,), flags=['multi_index', 'refs_ok', 'zerosize_ok'] + extras,
        op_flags=[op_flag], itershape=shape, order='C')
    with it:
        # never really has writebackifcopy semantics
        broadcast = it.itviews[0]
    result = _maybe_view_as_subclass(array, broadcast)
    if needs_writeable and not result.flags.writeable:
        result.flags.writeable = True
    return result 

def _compare_index_result(self, arr, index, mimic_get, no_copy):
        """Compare mimicked result to indexing result.
        """
        arr = arr.copy()
        indexed_arr = arr[index]
        assert_array_equal(indexed_arr, mimic_get)
        # Check if we got a view, unless its a 0-sized or 0-d array.
        # (then its not a view, and that does not matter)
        if indexed_arr.size != 0 and indexed_arr.ndim != 0:
            assert_(np.may_share_memory(indexed_arr, arr) == no_copy)
            # Check reference count of the original array
            if HAS_REFCOUNT:
                if no_copy:
                    # refcount increases by one:
                    assert_equal(sys.getrefcount(arr), 3)
                else:
                    assert_equal(sys.getrefcount(arr), 2)

        # Test non-broadcast setitem:
        b = arr.copy()
        b[index] = mimic_get + 1000
        if b.size == 0:
            return  # nothing to compare here...
        if no_copy and indexed_arr.ndim != 0:
            # change indexed_arr in-place to manipulate original:
            indexed_arr += 1000
            assert_array_equal(arr, b)
            return
        # Use the fact that the array is originally an arange:
        arr.flat[indexed_arr.ravel()] += 1000
        assert_array_equal(arr, b) 

def test_boolean_assignment_value_mismatch(self):
        # A boolean assignment should fail when the shape of the values
        # cannot be broadcast to the subscription. (see also gh-3458)
        a = np.arange(4)

        def f(a, v):
            a[a > -1] = v

        assert_raises(ValueError, f, a, [])
        assert_raises(ValueError, f, a, [1, 2, 3])
        assert_raises(ValueError, f, a[:1], [1, 2, 3]) 

def test_broadcast_in_args(self):
        # gh-5881
        arrs = [np.empty((6, 7)), np.empty((5, 6, 1)), np.empty((7,)),
                np.empty((5, 1, 7))]
        mits = [np.broadcast(*arrs),
                np.broadcast(np.broadcast(*arrs[:2]), np.broadcast(*arrs[2:])),
                np.broadcast(arrs[0], np.broadcast(*arrs[1:-1]), arrs[-1])]
        for mit in mits:
            assert_equal(mit.shape, (5, 6, 7))
            assert_equal(mit.ndim, 3)
            assert_equal(mit.nd, 3)
            assert_equal(mit.numiter, 4)
            for a, ia in zip(arrs, mit.iters):
                assert_(a is ia.base) 

def broadcast_to(array, shape, subok=False):
    """Broadcast an array to a new shape.

    Parameters
    ----------
    array : array_like
        The array to broadcast.
    shape : tuple
        The shape of the desired array.
    subok : bool, optional
        If True, then sub-classes will be passed-through, otherwise
        the returned array will be forced to be a base-class array (default).

    Returns
    -------
    broadcast : array
        A readonly view on the original array with the given shape. It is
        typically not contiguous. Furthermore, more than one element of a
        broadcasted array may refer to a single memory location.

    Raises
    ------
    ValueError
        If the array is not compatible with the new shape according to NumPy's
        broadcasting rules.

    Notes
    -----
    .. versionadded:: 1.10.0

    Examples
    --------
    >>> x = np.array([1, 2, 3])
    >>> np.broadcast_to(x, (3, 3))
    array([[1, 2, 3],
           [1, 2, 3],
           [1, 2, 3]])
    """
    return _broadcast_to(array, shape, subok=subok, readonly=True) 

def iter_base(self, xoff, yoff, win_xsize, win_ysize, **kwargs):
        '''
        Base iterator function to yield data from array-like window parameters.

        Parameters
        ----------
        xoff : array_like
            x offset(s) for the image regions to be read.
        yoff : array_like
            y offset(s) for the image regions to be read.
        win_xsize : array_like
            window x-dim size(s) for the image regions to be read.
        win_ysize : array_like
            window y-dim size(s) for the image regions to be read.
        kwargs : optional
            keyword arguments to be passed to get_data.

        Yields
        ------
        ndarray
            Three dimensional numpy array of data from the requested region
            of the image.

        '''

        logger.debug('*** begin iter_base ***')

        # Broadcast array_like
        windows = np.broadcast(xoff,yoff,win_xsize,win_ysize)

        # Iterate through windows generated from input parameters
        for w in windows:
            logger.debug('window parameters: xoff %s, yoff %s, '
                                            'win_xsize %s, win_ysize %s',
                                             w[0], w[1], w[2], w[3])
            yield self.get_data(window=w,**kwargs) 

def _check_broadcasting(self, array, reverse=False):
    """Test whether or not the given array can broadcast against this object"""
    import numpy as np

    if isinstance(array, type(self)):
        try:
            if reverse:
                np.broadcast(array, self)
            else:
                np.broadcast(self, array)
        except ValueError:
            return False
        else:
            return True
    else:
        if np.ndim(array) > np.ndim(self)-1:
            raise ValueError(f"Cannot broadcast array of {np.ndim(array)} dimensions against {type(self).__name__} "
                             f"object of fewer ({np.ndim(self)-1}) non-mode dimensions.\n"
                             "This is to ensure that scalars do not operate on individual "
                             "mode weights; they must operate on all simultaneously.\n"
                             "If that is the case and you still want to broadcast, add more "
                             "dimensions before this object's first dimension.")
        try:
            if reverse:
                np.broadcast(array, self[..., 0])
            else:
                np.broadcast(self[..., 0], array)
        except ValueError:
            return False
        else:
            return True 

def test_broadcast_single_arg(self):
        # gh-6899
        arrs = [np.empty((5, 6, 7))]
        mit = np.broadcast(*arrs)
        assert_equal(mit.shape, (5, 6, 7))
        assert_equal(mit.ndim, 3)
        assert_equal(mit.nd, 3)
        assert_equal(mit.numiter, 1)
        assert_(arrs[0] is mit.iters[0].base) 

def test_number_of_arguments(self):
        arr = np.empty((5,))
        for j in range(35):
            arrs = [arr] * j
            if j < 1 or j > 32:
                assert_raises(ValueError, np.broadcast, *arrs)
            else:
                mit = np.broadcast(*arrs)
                assert_equal(mit.numiter, j) 

def test_broadcast_error_kwargs(self):
        #gh-13455
        arrs = [np.empty((5, 6, 7))]
        mit  = np.broadcast(*arrs)
        mit2 = np.broadcast(*arrs, **{})
        assert_equal(mit.shape, mit2.shape)
        assert_equal(mit.ndim, mit2.ndim)
        assert_equal(mit.nd, mit2.nd)
        assert_equal(mit.numiter, mit2.numiter)
        assert_(mit.iters[0].base is mit2.iters[0].base)

        assert_raises(ValueError, np.broadcast, 1, **{'x': 1}) 

def add(self, other, subtraction=False):
    if isinstance(other, type(self)):
        if self.s != other.s:
            raise ValueError(f"Cannot add modes with different spin weights ({self.s} and {other.s})")
        s = self.s
        ell_min = min(self.ell_min, other.ell_min)
        ell_max = max(self.ell_max, other.ell_max)
        shape = np.broadcast(self[..., 0], other[..., 0]).shape + (LM_total_size(ell_min, ell_max),)
        result = np.zeros(shape, dtype=np.complex_)
        i_s1 = LM_total_size(ell_min, self.ell_min-1)
        i_s2 = i_s1+LM_total_size(self.ell_min, self.ell_max)
        i_o1 = LM_total_size(ell_min, other.ell_min-1)
        i_o2 = i_o1+LM_total_size(other.ell_min, other.ell_max)
        result[..., i_s1:i_s2] = self.view(np.ndarray)
        if subtraction:
            result[..., i_o1:i_o2] -= other.view(np.ndarray)
        else:
            result[..., i_o1:i_o2] += other.view(np.ndarray)
        metadata = copy.copy(self._metadata)
        metadata['spin_weight'] = s
        metadata['ell_min'] = ell_min
        metadata['ell_max'] = ell_max
        return type(self)(result, **metadata)
    elif np.any(other):
        raise ValueError(f"It is not permitted to add nonzero scalars to a {type(self).__name__} object")
    else:
        return np.add(self, other) 

def _check_broadcasting(self, array, reverse=False):
    """Test whether or not the given array can broadcast against this object"""
    import numpy as np

    if isinstance(array, type(self)):
        try:
            if reverse:
                np.broadcast(array, self)
            else:
                np.broadcast(self, array)
        except ValueError:
            return False
        else:
            return True
    else:
        if np.ndim(array) > np.ndim(self)-2:
            raise ValueError(f"Cannot broadcast array of {np.ndim(array)} dimensions against {type(self).__name__} "
                             f"object of fewer ({np.ndim(self)-2}) non-grid dimensions.\n"
                             "This is to ensure that scalars do not operate on individual "
                             "grid values; they must operate on all simultaneously.\n"
                             "If that is the case and you still want to broadcast, add more "
                             "dimensions before this object's first dimension.")
        try:
            if reverse:
                np.broadcast(array, self[..., 0, 0])
            else:
                np.broadcast(self[..., 0, 0], array)
        except ValueError:
            return False
        else:
            return True