GRBColumn#
- GRBColumn#
Gurobi column object. A column consists of a list of coefficient, constraint pairs. Columns are used to represent the set of constraints in which a variable participates, and the associated coefficients. They are temporary objects that typically have short lifespans.
You generally build columns by starting with an empty column (using the
GRBColumn
constructor), and then adding terms. Terms can be added individually, usingAddTerm
, or in groups, usingAddTerms
. Terms can also be removed from a column, usingRemove
.Individual terms in a column can be queried using the
GetConstr
, andGetCoeff
methods. You can query the number of terms in the column using theSize
property.- GRBColumn GRBColumn()#
Column constructor that creates an empty column.
- Returns:
An empty column object.
- Example:
// Create empty column object GRBColumn col = new GRBColumn();
' Create empty column object Dim col As GRBColumn = New GRBColumn()
- GRBColumn GRBColumn(GRBColumn orig)#
Column constructor that copies an existing column.
- Returns:
A copy of the input column object.
- Example:
// Copy an existing column GRBColumn col = new GRBColumn(col2);
' Copy an existing column Dim col As GRBColumn = New GRBColumn(col2)
- void AddTerm(double coeff, GRBConstr constr)#
Add a single term into a column.
- Parameters:
coeff – Coefficient for new term.
constr – Constraint for new term.
- Example:
// Add a pair (2.0, constr1) to column object col.AddTerm(2.0, constr1);
' Add a pair (2.0, constr1) to column object col.AddTerm(2.0, constr1)
- void AddTerms(double[] coeffs, GRBConstr[] constrs)#
Add a list of terms into a column. Note that the lengths of the two argument arrays must be equal.
- Parameters:
coeffs – Coefficients for added constraints.
constrs – Constraints to add to column.
- Example:
// Add 3 trivial linear constraints to model GRBConstr[] constrs = model.AddConstrs(3); // Constraint coefficients for variable x double[] coeffs = {1.0, 2.0, 3.0}; // Create and fill GRBColumn object GRBColumn col = new GRBColumn(); col.AddTerms(coeffs, constrs);
' Add 3 trivial linear constraints to model Dim constrs As GRBConstr() = model.AddConstrs(3) ' Constraint coefficients for variable x Dim coeffs As Double() = New Double() {1.0, 2.0, 3.0} ' Create and fill GRBColumn object Dim col As GRBColumn = New GRBColumn() col.AddTerms(coeffs, constrs)
- void AddTerms(double[] coeffs, GRBConstr[] constrs, int start, int len)#
Add new terms into a column. This signature allows you to use arrays to hold the coefficients and constraints that describe the terms in an array without being forced to add an term for each member in the array. The
start
andlen
arguments allow you to specify which terms to add.- Parameters:
coeffs – Coefficients for added constraints.
constrs – Constraints to add to column.
start – The first term in the list to add.
len – The number of terms to add.
- Example:
// Add 3 trivial linear constraints to model GRBConstr[] constrs = model.AddConstrs(3); // Constraint coefficients for variable x double[] coeffs = {1.0, 2.0, 3.0}; // Create and fill GRBColumn object, but use only first 2 pairs GRBColumn col = new GRBColumn(); col.AddTerms(coeffs, constrs, 0, 2);
' Add 3 trivial linear constraints to model Dim constrs As GRBConstr() = model.AddConstrs(3) ' Constraint coefficients for variable x Dim coeffs As Double() = New Double() {1.0, 2.0, 3.0} ' Create and fill GRBColumn object, but use only first 2 pairs Dim col As GRBColumn = New GRBColumn() col.AddTerms(coeffs, constrs, 0, 2)
- void Clear()#
Remove all terms from a column.
- Example:
col.Clear();
col.Clear()
- double GetCoeff(int i)#
Retrieve the coefficient from a single term in the column.
- Returns:
Coefficient for the term at index
i
in the column.- Example:
// Get the coefficient of first coefficient constraint pair double coeff = col.GetCoeff(0);
' Get the coefficient of first coefficient constraint pair Dim coeff As Double = col.GetCoeff(0)
- GRBConstr GetConstr(int i)#
Retrieve the constraint object from a single term in the column.
- Returns:
Constraint for the term at index
i
in the column.- Example:
// Get the constraint of first coefficient constraint pair GRBConstr constr = col.GetConstr(0);
' Get the constraint of first coefficient constraint pair Dim constr As GRBConstr = col.GetConstr(0)
- GRBConstr Remove(int i)#
Remove the term stored at index
i
of the column.- Parameters:
i – The index of the term to be removed.
- Returns:
The constraint whose term was removed from the column. Returns
null
if the specified index is out of range.- Example:
// Remove first coefficient constraint pair col.Remove(0);
' Remove first coefficient constraint pair col.Remove(0)
- boolean Remove(GRBConstr constr)#
Remove the term associated with constraint
constr
from the column.- Parameters:
constr – The constraint whose term should be removed.
- Returns:
Returns
true
if the constraint appeared in the column (and was removed).- Example:
// Remove pair associated with constr1 bool removed = col.Remove(constr1);
' Remove pair associated with constr1 Dim removed As Boolean = col.Remove(constr1)
- int Size#
(Property) The number of terms in the column.
- Example:
int s = col.Size;
Dim s As Integer = col.Size