add_variables#

add_variables(model, indexset, vartype, lb=None, ub=None, name=None, key_format=None)[source]#

Create and add multiple variables (corresponding to an index-set) to the DOcplex model.

This function extends DOcplex’s Model.xyz_var_dict methods by wrapping them and returning VarDict1D/VarDictND data structures - that can efficiently sum subsets of variables with a user-friendly syntax based on wildcard patterns.

Parameters:
modeldocplex.mp.model.Model

DOcplex model.

indexsetIndexSet1D or IndexSetND

Index-set for defining the variables. The name/names attribute of IndexSet1D/IndexSetND will be set as the key_name/key_names attribute of VarDict1D/VarDictND.

vartypestr

Variable type, in one of the following forms:

  • 'continuous' or 'C'

  • 'binary' or 'B'

  • 'integer' or 'I'

  • 'semicontinuous' or 'SC'

  • 'semiinteger' or 'SI'

lbint or float or sequence or function or ParamDict, optional

Lower bound, in one of the following forms:

  • A number - if all variables share the same lower bound.

  • A sequence of numbers - one for each variable.

  • A function - that returns a number when called on each element of index-set.

  • A ParamDict - with keys following the same structute as the index-set elements and values representing the lower bound; will fallback to None for index-set elements not found in ParamDict keys.

Default None corresponds to:

  • Continuous: 0

  • Binary: 0

  • Integer: 0

  • Semicontinuous: not applicable… will raise ValueError

  • Semiinteger: not applicable… will raise ValueError

ubint or float or sequence or function or ParamDict, optional

Upper bound, in one of the following forms:

  • A number - if all variables share the same upper bound.

  • A sequence of numbers - one for each variable.

  • A function - that returns a number when called on each element of the index-set.

  • A ParamDict - with keys following the same structute as the index-set elements and values representing the upper bound; will fallback to None for index-set elements not found in ParamDict keys.

Default None corresponds to 1 for binary variable type and infinity for other types.

namestr or function, optional

For naming variables, in one of the following forms:

  • A string - applied as a prefix to the string representation of each element of the index-set.

  • A function - that generates a name when called on each element of the index-set.

  • None.

Default is None. It will also be used as the value_name attribute of VarDict1D/VarDictND.

key_formatformat str (should include ‘%s’), optional

Defines how index-set elements are incorporated into variable names, by default '_%s'.

Returns:
VarDict1D or VarDictND
Raises:
ValueError

If the index-set is empty.

ValueError

If the variable type is invalid.

ValueError

If no lower bound is specified for Semicontinuous or Semiinteger variable type.

See also

add_variable

For a single variable.

Examples

Create DOcplex model:

>>> from docplex.mp.model import Model
>>> mdl = Model()

Create index-sets:

>>> nodes = IndexSet1D(['A', 'B', 'C'], name='node')
>>> arcs = IndexSetND([('A', 'B'), ('B', 'C'), ('C', 'B')], names=['ori', 'des'])

Add variables:

>>> node_select = add_variables(mdl, nodes, 'B', name='select')
>>> node_select
VarDict1D: node -> select
{'A': docplex.mp.Var(type=B,name='select_A'),
 'B': docplex.mp.Var(type=B,name='select_B'),
 'C': docplex.mp.Var(type=B,name='select_C')}

>>> arc_flow = add_variables(mdl, arcs, 'C', ub=10, name='flow')
>>> arc_flow
VarDictND: (ori, des) -> flow
{('A', 'B'): docplex.mp.Var(type=C,name='flow_A_B',ub=10),
 ('B', 'C'): docplex.mp.Var(type=C,name='flow_B_C',ub=10),
 ('C', 'B'): docplex.mp.Var(type=C,name='flow_C_B',ub=10)}
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