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import six
import warnings
import cupy
from cupy import core
zip_longest = six.moves.zip_longest
six_zip = six.moves.zip
# Shape map for atleast_nd functions
# (minimum dimension, input dimension) -> (output shape)
_atleast_nd_shape_map = {
(1, 0): lambda shape: (1,),
(2, 0): lambda shape: (1, 1),
(2, 1): lambda shape: (1,) + shape,
(3, 0): lambda shape: (1, 1, 1),
(3, 1): lambda shape: (1,) + shape + (1,),
(3, 2): lambda shape: shape + (1,),
}
def _atleast_nd_helper(n, arys):
"""Helper function for atleast_nd functions."""
res = []
for a in arys:
a = cupy.asarray(a)
if a.ndim < n:
new_shape = _atleast_nd_shape_map[(n, a.ndim)](a.shape)
a = a.reshape(*new_shape)
res.append(a)
if len(res) == 1:
res, = res
return res
def atleast_1d(*arys):
"""Converts arrays to arrays with dimensions >= 1.
Args:
arys (tuple of arrays): Arrays to be converted. All arguments must be
:class:`cupy.ndarray` objects. Only zero-dimensional array is
affected.
Returns:
If there are only one input, then it returns its converted version.
Otherwise, it returns a list of converted arrays.
.. seealso:: :func:`numpy.atleast_1d`
"""
return _atleast_nd_helper(1, arys)
def atleast_2d(*arys):
"""Converts arrays to arrays with dimensions >= 2.
If an input array has dimensions less than two, then this function inserts
new axes at the head of dimensions to make it have two dimensions.
Args:
arys (tuple of arrays): Arrays to be converted. All arguments must be
:class:`cupy.ndarray` objects.
Returns:
If there are only one input, then it returns its converted version.
Otherwise, it returns a list of converted arrays.
.. seealso:: :func:`numpy.atleast_2d`
"""
return _atleast_nd_helper(2, arys)
def atleast_3d(*arys):
"""Converts arrays to arrays with dimensions >= 3.
If an input array has dimensions less than three, then this function
inserts new axes to make it have three dimensions. The place of the new
axes are following:
- If its shape is ``()``, then the shape of output is ``(1, 1, 1)``.
- If its shape is ``(N,)``, then the shape of output is ``(1, N, 1)``.
- If its shape is ``(M, N)``, then the shape of output is ``(M, N, 1)``.
- Otherwise, the output is the input array itself.
Args:
arys (tuple of arrays): Arrays to be converted. All arguments must be
:class:`cupy.ndarray` objects.
Returns:
If there are only one input, then it returns its converted version.
Otherwise, it returns a list of converted arrays.
.. seealso:: :func:`numpy.atleast_3d`
"""
return _atleast_nd_helper(3, arys)
broadcast = core.broadcast
def broadcast_arrays(*args):
"""Broadcasts given arrays.
Args:
args (tuple of arrays): Arrays to broadcast for each other.
Returns:
list: A list of broadcasted arrays.
.. seealso:: :func:`numpy.broadcast_arrays`
"""
return list(broadcast(*args).values)
def broadcast_to(array, shape):
"""Broadcast an array to a given shape.
Args:
array (cupy.ndarray): Array to broadcast.
shape (tuple of int): The shape of the desired array.
Returns:
cupy.ndarray: Broadcasted view.
.. seealso:: :func:`numpy.broadcast_to`
"""
return core.broadcast_to(array, shape)
def expand_dims(a, axis):
"""Expands given arrays.
Args:
a (cupy.ndarray): Array to be expanded.
axis (int): Position where new axis is to be inserted.
Returns:
cupy.ndarray: The number of dimensions is one greater than that of
the input array.
.. seealso:: :func:`numpy.expand_dims`
"""
# TODO(okuta): check type
shape = a.shape
if axis < 0:
axis = axis + len(shape) + 1
if axis > a.ndim or axis < 0:
# TODO(unno): Too large and too small axis is deprecated in NumPy 1.13
# We need to fix this behavior after NumPy forbids it.
warnings.warn(
'Both axis > a.ndim and axis < -a.ndim - 1 are deprecated and '
'will raise an AxisError in the future.',
DeprecationWarning)
return a.reshape(shape[:axis] + (1,) + shape[axis:])
def squeeze(a, axis=None):
"""Removes size-one axes from the shape of an array.
Args:
a (cupy.ndarray): Array to be reshaped.
axis (int or tuple of ints): Axes to be removed. This function removes
all size-one axes by default. If one of the specified axes is not
of size one, an exception is raised.
Returns:
cupy.ndarray: An array without (specified) size-one axes.
.. seealso:: :func:`numpy.squeeze`
"""
# TODO(okuta): check type
return a.squeeze(axis)
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