PyGurobi package documentation¶

pygurobi module¶

Module contents¶

Functions to support rapid interactive modification of Gurobi models.

For reference on Gurobi objects such as Models, Variables, and Constraints, see the Gurobi Python API.

See the PyGurobi Github page for a tutorial

pygurobi.add_constraint_constant(model, variables, constant, sense='<', con_name='')¶

Add constraint to model that says the sum of variables must be equal, less than or equal, or, greater than or equal, a constant.

Parameters

model: Gurobi model object
variables: List of Gurobi variables
constant: Any number
sense: one of ">", "<", "=", representing greater than or equal, less than or equal, and equal, respectively.
con_name: name of the to be added constraint

pygurobi.add_constraint_variables(model, variables1, variables2, sense='=', con_name='')¶

Add constraint to model that says the sum of a list of variables must be equal, less than or equal, or greater than or equal, the sum of another list of variables.

Parameters

model: Gurobi model object
variables1: List of Gurobi variables composing the left hand side of the constraint
variables2: List of Gurobi variables composing the right hand side of the constraint
constant: Any number
sense: one of ">", "<", "=", representing greater than or equal, less than or equal, and equal, respectively.
con_name: name of the to be added constraint

pygurobi.filter_constraints(constraints, filter_values, exclude=False)¶

Return a new list of constraints that match the filter values from the given constraints list.

Parameters

constraints: List of Gurobi constraint objects
filter_values: Dictionary mapping index numbers to index values. For example {0: "a", 1: "b"} returns constraints with first index value of "a" and second index value of "b".
exclude: If True return the complement of of the constraints that match the filter values.

pygurobi.filter_variables(variables, filter_values, exclude=False)¶

Return a new list of variables that match the filter values from the given variables list.

Parameters

variables: List of Gurobi variable objects
filter_values: Dictionary mapping index numbers to index values. For example {0: "a", 1: "b"} returns variables with first index value of "a" and second index value of "b".
exclude: If True return the complement of of the constraints that match the filter values.

pygurobi.get_constraints(model, name='', approx=False, filter_values={}, exclude=False)¶

Return a list of constraints from the model selected by constraint set name.

A constraint set is composed of all constraints sharing the same string identifier before the indices: A(2,3,4) and A(1,2,3) are in the same constraint set, A; A(2,3,4) and B(2,3,4) are in constraint sets A and B, respectively

PyGurobi by default assumes that constraint set names are separated from indices by round brackets "(" and ")". For example, constraints look like env(r,t) - where "env" in the constraint set name and "r" and "t" are the index values. See the source for more details.

Parameters

model: Gurobi model object
name: Name of constraint set
filter_values: Dictionary mapping index numbers to index values. For example {0: "a", 1: "b"} returns constraints with first index value of "a" and second index value of "b".
exclude: If True return the complement of of the constraints that match the filter values.

pygurobi.get_constraints_attr(attr, model='', name='', constraints='')¶

Return a dictionary of constraint names and their corresponding attribute value.

Specifiy either model and name parameters or supply a list of constraints

Parameters

attr: Gurobi constraints attribute name
model: Gurobi model object
name: Name of constraint set
constraints: List of Gurobi constraint objects

pygurobi.get_constraints_by_index(index, model='', name='', constraints='')¶

Return a dictionary mapping index values to lists of constraints having that index value.

Specifiy either model and name parameters or supply a list of constraints

Parameters

index: Index number using Python list indexing - 0 corresponds to the first index.
model: Gurobi model object
name: Name of constraint set
constraints: List of Gurobi constraint objects

pygurobi.get_linexp_by_index(index, model='', name='', variables='')¶

Return a dictionary of index values to Gurobi linear expressions corresponding to the summation of variables that match the index value for the given index number.

Specifiy either model and name parameters or supply a list of variables

Parameters

index: Index number using Python list indexing - 0 corresponds to the first index.
model: Gurobi model object
name: Name of variables set
variables: List of Gurobi variable objects

pygurobi.get_linexp_from_variables(variables)¶

Return a linear expression from the supplied list of variables.

Parameters

variables: List of Gurobi variable objects

pygurobi.get_variables(model, name='', approx=False, filter_values={}, exclude=False)¶

Return a list of variables from the model selected by variable set name.

A variable set is composed of all variables sharing the same string identifier before the indices: A[2,3,4] and A[1,2,3] are in the same variable set, A; A[2,3,4] and B[2,3,4] are in varible sets A and B, respectively

PyGurobi by default assumes that *variable names* are separated from indices by square brackets "[" and "]", For example, variables look like x[i,j] - "x" in the variable set name, and "i" and "j" and the variable's index values. See the source code for more details.

Parameters

model: Gurobi model object
name: Name of variable set
filter_values: Dictionary mapping index numbers to index values. For example {0: "a", 1: "b"} returns variables with first index value of "a" and second index value of "b".
exclude: If True return the complement of of the variables that match the filter values.

pygurobi.get_variables_attr(attr, model='', name='', variables='')¶

Return a dictionary of variables names and their corresponding attribute value.

Specifiy either model and name parameters or supply a list of variables

Parameters

attr: Gurobi variables attribute name
model: Gurobi model object
name: Name of variable set
variables: List of Gurobi variables objects

pygurobi.get_variables_by_index(index, model='', name='', variables='')¶

Return a dictionary mapping index values to lists of matching variables.

Specifiy either model and name parameters or supply a list of variables

Parameters

index: Index number using Python list indexing - 0 corresponds to the first index.
model: Gurobi model object
name: Name of variable set
variables: List of Gurobi variable objects

pygurobi.get_variables_by_two_indices(index1, index2, model='', name='', variables='')¶

Return a dictionary of variables mapping index1 values to dictionaries mapping index2 values to matching variables.

Specifiy either model and name parameters or supply a list of variables

Parameters

index1: Index number using Python list indexing - 0 corresponds to the first index.
index2: Index number using Python list indexing - 0 corresponds to the first index.
model: Gurobi model object
name: Name of variable set
variables: List of Gurobi variable objects

pygurobi.graph_by_index(model, variables, index, title='', y_axis='', x_axis='')¶

Display a graph of variables against the specified index.

Matplotlib must already be installed to use this. See: http://matplotlib.org/faq/installing_faq.html

Parameters

model: Gurobi model object
variables: List of Gurobi variable objects
index: Index number using Python list indexing - 0 corresponds to the first index.
title: Graph title
y_axis: Title for y-axis
x_axis: Title for x-axis

pygurobi.graph_by_two_indices(model, variables, index1, index2, title='', y_axis='', x_axis='')¶

Display a graph of the variable summed over index2 against index1.

Matplotlib must already be installed to use this. See: http://matplotlib.org/faq/installing_faq.html

Parameters

model: Gurobi model object
variables: List of Gurobi variable objects
index1: Index number using Python list indexing - 0 corresponds to the first index.
index2: Index number using Python list indexing - 0 corresponds to the first index.
title: Graph title
y_axis: Title for y-axis
x_axis: Title for x-axis

pygurobi.list_constraints(model)¶

Print to screen the constraint sets in the model. Show the name of each constraint set along with the number of constraints in that set.

A constraint set is composed of all constraints sharing the same string identifier before the indices: A(2,3,4) and A(1,2,3) are in the same constraint set, A; A(2,3,4) and B(2,3,4) are in constraint sets A and B, respectively

Parameters

model: Gurobi model object

pygurobi.list_variables(model)¶

Print to screen the variable sets in the model. Show the name of each variable set along with the number of variables in that set.

A variable set is composed of all variables sharing the same string identifier before the indices: A[2,3,4] and A[1,2,3] are in the same variable set, A; A[2,3,4] and B[2,3,4] are in variable sets A and B, respectively

Parameters

model: Gurobi model object

pygurobi.print_constraints(constraints)¶

Print a list of constraints to screen

Parameters

constraints: List of Gurobi constraint objects

pygurobi.print_constraints_attr(attr, model='', name='', constraints='')¶

Print to screen a list of constraint attribute values given by the constraints specified in the names parameter.

Specifiy either model and name parameters or supply a list of constraints

Parameters

attr: Gurobi constraints attribute name
model: Gurobi model object
name: Name of constraint set
constraints: List of Gurobi constraint objects

pygurobi.print_dict(dictionary)¶

Print a dictionary to screen.

Parameters

dictionary: Python dictionary

pygurobi.print_two_indices_dict(indices_dict)¶

Print to screen a two level nested dictionary.

Parameters

dictionary: Two level Python dictionary: e.g. a = {1: {2: 3}}

pygurobi.print_variables(variables)¶

Print a list of variables.

Parameters

variables: List of Gurobi variable objects.

pygurobi.print_variables_attr(attr, model='', name='', variables='')¶

Print to screen a dictionary of variables names and their corresponding attribute value.

Specifiy either model and name parameters or supply a list of variables

Parameters

attr: Gurobi variables attribute name
model: Gurobi model object
name: Name of variable set
variables: List of Gurobi variables objects

pygurobi.print_variables_sum_by_index(index, model='', name='', variables='')¶

Print a dictionary of variables, summed by the specified index.

Parameters

index: Index number using Python list indexing - 0 corresponds to the first index.
model: Gurobi model object
name: Name of variable set
variables: List of Gurobi variables objects

pygurobi.read_model(filename)¶

Read a model using gurobipy.

Parameters

filename: Gurobi compatible file describing an optimization model.

pygurobi.remove_constraints_from_model(model, name='', constraints='')¶

Remove the given constraints from the model.

Specifiy either model and name parameters or supply a list of constraints

Parameters

model: Gurobi model object
name: Name of constraint set
constraints: List of Gurobi constraints

pygurobi.remove_variables_from_model(model, name='', variables='')¶

Remove the given variables from the model.

Specifiy either model and name parameters or supply a list of constraints

Parameters

model: Gurobi model object
name: Name of variable set
variables: List of Gurobi variables

pygurobi.reoptimize(m)¶

Update, reset, and optimize a model.

Parameters

model: Gurobi model object

pygurobi.set_constraints_attr(attr, val, model='', name='', constraints='')¶

Set an attribute of a model constraint set.

Specifiy either model and name parameters or supply a list of constraints

Parameters

attr: Gurobi constraints attribute name
val: Constraint attribute value
model: Gurobi model object
name: Name of variable set
constraints: List of Gurobi constraints

pygurobi.set_constraints_rhs_as_percent(percent, model='', name='', constraints='')¶

Set the right hand side (rhs) of a constraint set as a percentage of its current rhs.

Specifiy either model and name parameters or supply a list of constraints

Parameters

percent: Number between 0 and 1
model: Gurobi model object
name: Name of variable set
constraints: List of Gurobi constraints

pygurobi.set_variables_attr(attr, val, model='', name='', variables='')¶

Set an attribute of a model variable set.

Specifiy either model and name parameters or supply a list of variables

Parameters

attr: Gurobi variables attribute name
val: Variable attribute value
model: Gurobi model object
name: Name of variable set
variables: List of Gurobi variables

pygurobi.set_variables_bounds(lb='', ub='', model='', name='', variables='')¶

Set the lower bound and/or upper bound for a variables set.

Specifiy either model and name parameters or supply a list of variables

Parameters

lb: Variable set lower bound
val: Variable set upper bound
model: Gurobi model object
name: Name of variable set
variables: List of Gurobi variables

pygurobi.sum_variables_by_index(index, model='', name='', variables='')¶

Return a dictionary mapping index values to the sum of the solution values of all matching variables.

Specifiy either model and name parameters or supply a list of variables

Parameters

index: Index number using Python list indexing - 0 corresponds to the first index.
model: Gurobi model object
name: Name of variable set
variables: List of Gurobi variables

pygurobi.sum_variables_by_two_indices(index1, index2, model='', name='', variables='')¶

Return a dictionary mapping index1 values to dictionaries of the given variables summed over index2.

Parameters

index1: Index number using Python list indexing - 0 corresponds to the first index.
index2: Index number using Python list indexing - 0 corresponds to the first index.
model: Gurobi model object
name: Name of variable set
variables: List of Gurobi variables

pygurobi.zero_all_objective_coeffs(model)¶

Set all variable objective coefficients in a model to zero.

Parameters

model: Gurobi model object

PyGurobi package documentation¶

pygurobi module¶

Module contents¶

Table Of Contents

Related Topics

This Page