# Source code for cvxpy.atoms.affine.reshape

"""
Copyright 2013 Steven Diamond

This file is part of CVXPY.

CVXPY is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

CVXPY is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with CVXPY.  If not, see <http://www.gnu.org/licenses/>.
"""

from cvxpy.atoms.affine.affine_atom import AffAtom
import cvxpy.lin_ops.lin_utils as lu
import numpy as np

[docs]class reshape(AffAtom):
"""Reshapes the expression.

Vectorizes the expression then unvectorizes it into the new shape.
The entries are reshaped and stored in column-major order, also known
as Fortran order.

Parameters
----------
expr : Expression
The expression to promote.
shape : tuple
The shape to promote to.
"""

def __init__(self, expr, shape):
self._shape = shape
super(reshape, self).__init__(expr)

@AffAtom.numpy_numeric
def numeric(self, values):
"""Reshape the value.
"""
return np.reshape(values[0], self.shape, "F")

def validate_arguments(self):
"""Checks that the new shape has the same number of entries as the old.
"""
old_len = self.args[0].size
new_len = np.prod(self._shape, dtype=int)
if not old_len == new_len:
raise ValueError(
"Invalid reshape dimensions %s." % (self._shape,)
)

def shape_from_args(self):
"""Returns the shape from the rows, cols arguments.
"""
return self._shape

def get_data(self):
"""Returns info needed to reconstruct the expression besides the args.
"""
return [self._shape]

@staticmethod
def graph_implementation(arg_objs, shape, data=None):
"""Convolve two vectors.

Parameters
----------
arg_objs : list
LinExpr for each argument.
shape : tuple
The shape of the resulting expression.
data :
Additional data required by the atom.

Returns
-------
tuple
(LinOp for objective, list of constraints)
"""
return (lu.reshape(arg_objs[0], shape), [])