8.7.6. MVar¶

class MVar¶

A multidimensional array of variables. Generally, it is returned by Model.addMVar() . You can also wrap an existing array to obtain a MVar, for example, MVar.fromlist() .

Properties

`T`	Obtain the transpose of MVar
`ndim`	Number of MVar dimensions
`shape`	Shape of MVar
`size`	Number of variables contained in MVar

T¶: Obtain the transpose of MVar

ndim¶: Number of MVar dimensions

shape¶: Shape of MVar

size¶: Number of variables contained in MVar

Static Methods

`fromlist()`	Wrap a set of variables as a MVar
`fromvar()`	Wrap a variable as a MVar

Methods

`copy()`	Return a copy of the current MVar
`diagonal()`	Obtain the diagonal elements of the matrix MVar
`getAttr()`	Obtain the attribute values associated with MVar
`item()`	Obtain the unique variable contained in the current MVar
`reshape()`	Return a MVar with the same data but a new shape
`setAttr()`	Set the attribute values associated with MVar
`sum()`	Return a linear expression that sums all variables in MVar
`tolist()`	Return an array of all variables in the current MVar
`transpose()`	The transpose of a matrix variable (MVar)

fromlist(li)¶

Wrap a set of variables as a MVar

Parameters: li – List of variables

example:

m = Model()
mat = MVar.fromlist([x0, x1, x2, x3]).reshape(2, 2)

fromvar(var)¶

Wrap a variable as a MVar

Parameters: var – Variables to be packaged

example:

mat11 = MVar.fromvar(x)

copy()¶

Return a copy of the current MVar.

example:

mat1 = mat.copy()

diagonal()¶

Obtain the diagonal elements of the matrix MVar.

example:

print(mat.diagonal())

getAttr(attrname)¶

Obtain the attribute values associated with MVar.

Parameters: attrname – The name of the attribute.

example:

m = Model()
mat = m.addMVar((2, 2))
print(mat.lb)
print(mat.getAttr(MDO.Attr.LB))

Note

Attribute can also be read and written directly through object attributes; in this case, the attribute name is case-insensitive.

item()¶

Obtain the unique variable contained in the current MVar.

example:

mat = m.addMVar((2, 2))
first = mat[0, 0]
print(type(first))
print(type(first.item()))

Note

If the current MVar contains more than one variable, an exception is thrown.

reshape(*shape)¶

Return a MVar with the same data but a new shape.

Parameters

*shape –

New shape

example:

m = Model()
mat = m.addMVar((2, 2))
x = mat.reshape(1, 4)  # default to fold along rows
x_c = mat.reshape(-1, order='C')  # fold along rows
x_f = mat.reshape(-1, order='F')  # fold along columns

setAttr(attrname, attrvalues)¶

Set the attribute values associated with MVar.

Parameters

attrname – The name of the attribute to be set.
attrvalues – The new value of the attribute to be set. Can be scalar or array.

example:

m = Model()
mat = m.addMVar((2, 2))
mat.lb = [1.0, 2.0, 3.0, 4.0]
mat.setAttr(MDO.Attr.LB, 5.0)

Note

Attributes can also be read and written directly through object attributes; in this case, the attribute name is case-insensitive.

sum(axis=None)¶

Return a linear expression that sums all variables in MVar

Parameters: axis=None – Sum along the specified axis

example:

linExpr = mat.sum()

tolist()¶

Return an array of all variables in the current MVar

example:

mat = m.addMVar((2,))
x = mat.tolist()
print(x[0] ** 2 + 2 * x[0] * x[1] + x[1] ** 2)

transpose()¶

The transpose of a matrix variable (MVar)

example:

print(mat.transpose())