gurobipy.GRB#

class GRB#

GRB exposes a set of constants for numeric codes and strings used in the Gurobi API. These constants cover the possible values of many method arguments and status values that occur in gurobipy code. For example, to create a binary variable using Model.addVar, you would use GRB.BINARY:

from gurobipy import GRB
...
x = model.addVar(vtype=GRB.BINARY)

To set the objective direction in a call to Model.setObjective, you would use GRB.MINIMIZE or GRB.MAXIMIZE:

model.setObjective(x + y + z, sense=GRB.MAXIMIZE)

Some constants are defined directly in GRB while others are defined in the sub-namespaces GRB.Attr, GRB.Callback, GRB.Error, GRB.Param, and GRB.Status.

List of GRB constants

The following constants are members of the GRB class. They are accessible as, for example, GRB.LOADED.

# Status codes

LOADED          = 1
OPTIMAL         = 2
INFEASIBLE      = 3
INF_OR_UNBD     = 4
UNBOUNDED       = 5
CUTOFF          = 6
ITERATION_LIMIT = 7
NODE_LIMIT      = 8
TIME_LIMIT      = 9
SOLUTION_LIMIT  = 10
INTERRUPTED     = 11
NUMERIC         = 12
SUBOPTIMAL      = 13
INPROGRESS      = 14
USER_OBJ_LIMIT  = 15
WORK_LIMIT      = 16
MEM_LIMIT       = 17

# Batch status codes

BATCH_CREATED   = 1
BATCH_SUBMITTED = 2
BATCH_ABORTED   = 3
BATCH_FAILED    = 4
BATCH_COMPLETED = 5

# Constraint senses

LESS_EQUAL    = '<'
GREATER_EQUAL = '>'
EQUAL         = '='

# Variable types

CONTINUOUS = 'C'
BINARY     = 'B'
INTEGER    = 'I'
SEMICONT   = 'S'
SEMIINT    = 'N'

# Objective sense

MINIMIZE = 1
MAXIMIZE = -1

# SOS types

SOS_TYPE1 = 1
SOS_TYPE2 = 2

# General constraint types

GENCONSTR_MAX       = 0
GENCONSTR_MIN       = 1
GENCONSTR_ABS       = 2
GENCONSTR_AND       = 3
GENCONSTR_OR        = 4
GENCONSTR_NORM      = 5
GENCONSTR_INDICATOR = 6
GENCONSTR_PWL       = 7
GENCONSTR_POLY      = 8
GENCONSTR_EXP       = 9
GENCONSTR_EXPA      = 10
GENCONSTR_LOG       = 11
GENCONSTR_LOGA      = 12
GENCONSTR_POW       = 13
GENCONSTR_SIN       = 14
GENCONSTR_COS       = 15
GENCONSTR_TAN       = 16
GENCONSTR_LOGISTIC  = 17

# Basis status

BASIC          = 0
NONBASIC_LOWER = -1
NONBASIC_UPPER = -2
SUPERBASIC     = -3

# Numeric constants

INFINITY  = 1e100
UNDEFINED = 1e101
MAXINT    = 2000000000

# Limits

MAX_NAMELEN    = 255
MAX_STRLEN     = 512
MAX_TAGLEN     = 10240
MAX_CONCURRENT = 64

# Other constants

DEFAULT_CS_PORT = 61000

# Version number

VERSION_MAJOR     = 11
VERSION_MINOR     = 0
VERSION_TECHNICAL = 3

# Errors

ERROR_OUT_OF_MEMORY            = 10001
ERROR_NULL_ARGUMENT            = 10002
ERROR_INVALID_ARGUMENT         = 10003
ERROR_UNKNOWN_ATTRIBUTE        = 10004
ERROR_DATA_NOT_AVAILABLE       = 10005
ERROR_INDEX_OUT_OF_RANGE       = 10006
ERROR_UNKNOWN_PARAMETER        = 10007
ERROR_VALUE_OUT_OF_RANGE       = 10008
ERROR_NO_LICENSE               = 10009
ERROR_SIZE_LIMIT_EXCEEDED      = 10010
ERROR_CALLBACK                 = 10011
ERROR_FILE_READ                = 10012
ERROR_FILE_WRITE               = 10013
ERROR_NUMERIC                  = 10014
ERROR_IIS_NOT_INFEASIBLE       = 10015
ERROR_NOT_FOR_MIP              = 10016
ERROR_OPTIMIZATION_IN_PROGRESS = 10017
ERROR_DUPLICATES               = 10018
ERROR_NODEFILE                 = 10019
ERROR_Q_NOT_PSD                = 10020
ERROR_QCP_EQUALITY_CONSTRAINT  = 10021
ERROR_NETWORK                  = 10022
ERROR_JOB_REJECTED             = 10023
ERROR_NOT_SUPPORTED            = 10024
ERROR_EXCEED_2B_NONZEROS       = 10025
ERROR_INVALID_PIECEWISE_OBJ    = 10026
ERROR_UPDATEMODE_CHANGE        = 10027
ERROR_CLOUD                    = 10028
ERROR_MODEL_MODIFICATION       = 10029
ERROR_CSWORKER                 = 10030
ERROR_TUNE_MODEL_TYPES         = 10031
ERROR_SECURITY                 = 10032
ERROR_NOT_IN_MODEL             = 20001
ERROR_FAILED_TO_CREATE_MODEL   = 20002
ERROR_INTERNAL                 = 20003

# Cuts parameter values

CUTS_AUTO           = -1
CUTS_OFF            = 0
CUTS_CONSERVATIVE   = 1
CUTS_AGGRESSIVE     = 2
CUTS_VERYAGGRESSIVE = 3

# Presolve parameter values

PRESOLVE_AUTO         = -1
PRESOLVE_OFF          = 0
PRESOLVE_CONSERVATIVE = 1
PRESOLVE_AGGRESSIVE   = 2

# Method parameter values

METHOD_NONE                             = -1
METHOD_AUTO                             = -1
METHOD_PRIMAL                           = 0
METHOD_DUAL                             = 1
METHOD_BARRIER                          = 2
METHOD_CONCURRENT                       = 3
METHOD_DETERMINISTIC_CONCURRENT         = 4
METHOD_DETERMINISTIC_CONCURRENT_SIMPLEX = 5

# BarHomogeneous parameter values

BARHOMOGENEOUS_AUTO = -1
BARHOMOGENEOUS_OFF  = 0
BARHOMOGENEOUS_ON   = 1

# BarOrder parameter values

BARORDER_AUTOMATIC        = -1
BARORDER_AMD              = 0
BARORDER_NESTEDDISSECTION = 1

# MIPFocus parameter values

MIPFOCUS_BALANCED    = 0
MIPFOCUS_FEASIBILITY = 1
MIPFOCUS_OPTIMALITY  = 2
MIPFOCUS_BESTBOUND   = 3

# SimplexPricing parameter values

SIMPLEXPRICING_AUTO           = -1
SIMPLEXPRICING_PARTIAL        = 0
SIMPLEXPRICING_STEEPEST_EDGE  = 1
SIMPLEXPRICING_DEVEX          = 2
SIMPLEXPRICING_STEEPEST_QUICK = 3

# VarBranch parameter values

VARBRANCH_AUTO           = -1
VARBRANCH_PSEUDO_REDUCED = 0
VARBRANCH_PSEUDO_SHADOW  = 1
VARBRANCH_MAX_INFEAS     = 2
VARBRANCH_STRONG         = 3

# Partition parameter values

PARTITION_EARLY     = 16
PARTITION_ROOTSTART = 8
PARTITION_ROOTEND   = 4
PARTITION_NODES     = 2
PARTITION_CLEANUP   = 1

# Callback phase values

PHASE_MIP_NOREL   = 0
PHASE_MIP_SEARCH  = 1
PHASE_MIP_IMPROVE = 2

# FeasRelax method parameter values

FEASRELAX_LINEAR      = 0
FEASRELAX_QUADRATIC   = 1
FEASRELAX_CARDINALITY = 2

GRB.Attr#

The constants defined in GRB.Attr cover the names listed in the Attributes reference. They correspond to possible values of the attrname argument of methods used to get or set attributes (Model.getAttr, Model.setAttr, for example). These constants are simply strings, so wherever you might use them, you also have the option of using the string directly. For example, GRB.Attr.Obj is equal to the string "Obj".

Example:

x = model.addVar()
x.setAttr(GRB.Attr.PoolIgnore, 1)

GRB.Callback#

The constants defined in GRB.Callback cover the codes listed in the Callback Codes reference. They correspond to possible values of the where argument passed to the user callback during optimization, and values accepted by the what argument of Model.cbGet to query data within the user callback.

Example:

def callback(model, where):
    if where == GRB.Callback.MIP:
        best_objective = model.cbGet(GRB.Callback.MIP_OBJBST)
        ...

GRB.Error#

The constants defined in GRB.Error cover the codes listed in the Error Codes reference. They correspond to possible values of GurobiError.errno when handling exceptions raised by gurobipy.

Example:

try:
    with gp.Env() as env:
        ...
except gp.GurobiError as e:
    if e.errno == GRB.Error.NETWORK:
        ...
    elif e.errno == GRB.Error.JOB_REJECTED:
        ...
    else:
        ...

GRB.Param#

The constants defined in GRB.Param cover the names listed in the Parameters reference. They correspond to possible values of the paramname argument of Model.setParam or Env.setParam. These constants are simply strings, so wherever you might use them, you also have the option of using the string directly. For example, GRB.Param.DisplayInterval is equal to the string "DisplayInterval".

Example:

model.setParam(GRB.Param.MIPGap, 1e-2)

GRB.Status#

The constants defined in GRB.Status cover the codes listed in the Status Codes reference. They correspond to values of the Status attribute of the Model object.

Example:

model.optimize()
if model.Status == GRB.Status.OPTIMAL:
    ...
elif model.Status == GRB.Status.INFEASIBLE:
    ...
else:
    ...

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