AMPL Class¶

An AMPL translator. An object of this class can be used to do the following tasks:

Run AMPL code. See ampl.AMPL.Eval.

Read models and data from files. See ampl.AMPL.read and ampl.AMPL.ReadData.

Solve optimization problems constructed from model and data (see ampl.AMPL.Solve).

Access single elements of an optimization problem. See the generic ampl.AMPL.GetEntity and the generic ampl.AMPL.GetVariable, ampl.AMPL.GetObjective, ampl.AMPL.GetConstraint, ampl.AMPL.GetSet and ampl.AMPL.GetParameter.

Access lists of available elements of an optimization problem. See ampl.AMPL.GetVariables, ampl.AMPL.GetObjectives, ampl.AMPL.GetConstraints, ampl.AMPL.GetSets and ampl.AMPL.GetParameters.

AMPL stores one or more problems which may consume substantial amount of memory. An AMPL object without any references to it will eventually be freed by the Java garbage collector and all the memory and other resources associated with it will be released. This includes any resources which are out of scope of the garbage collector such as open files or memory managed by the native code. Call ampl.AMPL.Close to release these resources explicitly.

The initialization of the Java representation of the AMPL entities (any class derived from ampl.Entities.Entity) is lazy and consists of two steps. When a function listing available elements is called, only a shallow list with names, types and declarations of the elements is populated. The same happens when a reference to a Java representation of one entity is obtained (through a call to ampl.AMPL.GetEntity or any other single entity factory function). When accessing any instance of an entity (through the methods 'get' of any class), the (memory hungry) list of instances for that entity is created.

Consistency is maintained automatically. Any command issued to the translator through ampl.AMPL.Eval and similar functions invalidates all entities, and any further access to any entity will require communication between the native translator and the Java code. Conversely, any operation called through the Java equivalent function, like fixing variables or solving the model will invalidate only the entities involved. A list of dependencies between entities is automatically updated.

Error handling is two-faced:

1. Errors coming from the underlying AMPL translator (e.g. syntax errors and warnings obtained calling the ampl.AMPL.Eval method) are handled by the event ampl.AMPL.Error. Note that by default the event is disabled. To enable it, call ampl.AMPL.EnableErrorAndWarningRouting.

2. Generic errors coming from misusing the API, which are detected in .NET, are thrown as exceptions.

The default implementation of the error handler throws exceptions on errors and prints to console on warnings.

The output of every user interaction with the underlying translator is handled by the event ampl.AMPL.Output, which is called at each block of output from the translator after the function ampl.AMPL.EnableOutputRouting is called.

Namespace

ampl

Assemblies

AMPL

Inheritance Hierarchy
Syntax
Constructors
Methods
Properties
Events

Inheritance Hierarchy ¶

System.Object
ampl.AMPL

Syntax ¶

[ComVisible(false)]
public class AMPL : IDisposable

class ampl.AMPL

Constructors ¶

AMPL()¶

Default constructor: creates a new AMPL instance with the default environment.

public AMPL()

AMPL(ampl.Environment)

Creates a new AMPL instance with the specified environment

public AMPL(Environment e)

Methods ¶

Cd(System.String)¶

Change or display the current working directory (see https://en.wikipedia.org/wiki/Working_directory ).

Arguments: directoryName (System.String) – New working directory or null (to display the working directory)
Return type: System.String

public string Cd(string directoryName = null)

Close()¶

Stops the underlying engine and release its resources. Any further attempt to execute optimisation commands without restarting it will throw an exception.

public void Close()

Display(System.String[])¶

public void Display(params string[] args)

Dispose()¶

public void Dispose()

Dispose(System.Boolean)

protected virtual void Dispose(bool disposing)

EnableErrorAndWarningRouting()¶

Enable routing of AMPL error and warning handling via the C# wrapper. Must be called to enable handling of errors and warning through handlers registered with ampl.AMPL.Error and ampl.AMPL.Warning.

public void EnableErrorAndWarningRouting()

EnableOutputRouting()¶

Enable routing of AMPL console outputs through the C# wrapper. Must be called to enable handling of the output through a personalised handler registered with ampl.AMPL.Output.

public void EnableOutputRouting()

Eval(System.String)¶

Parses AMPL code and evaluates it as a possibly empty sequence of AMPL declarations and statements. As a side effect, it invalidates all entities (as the passed statements can contain any arbitrary command); the lists of entities will be re-populated lazily (at first access) The output of interpreting the statements is passed to the current OutputHandler (see getOutputHandler and setOutputHandler). By default, errors are reported as exceptions and warnings are printed on stdout. This behavior can be changed reassigning an ErrorHandler using setErrorHandler.

Arguments: AMPLStatements (System.String) – A collection of AMPL statements and declarations to be passed to the interpreter

public void Eval(string AMPLStatements)

EvalAsync(System.String, System.Action)¶

Interpret asynchronously the given AMPL statements

Arguments: cb (System.Action) – Call back to be executed when completed

public void EvalAsync(string AMPLStatements, Action cb)

Expand(ampl.Entities.Entity[])¶

public void Expand(params Entity[] entities)

ExportData(System.Boolean)¶

Get all the data currently loaded in dat format

Arguments: includeSets (System.Boolean) – True to include set members in the export, false to exclude them
Return type: System.String

public string ExportData(bool includeSets = true)

ExportData(System.String, System.Boolean)

Writes all the data currently loaded to file in dat format

Arguments

fileName (System.String) – The file to write
includeSets (System.Boolean) – True to include set members in the export, false to exclude them

public void ExportData(string fileName, bool includeSets = true)

ExportModel()¶

Returns all the declarations in the current AMPL instance

Return type: System.String

public string ExportModel()

ExportModel(System.String)

Writes the declarations in the current AMPL instance to file

Arguments: fileName (System.String) – The file to write

public void ExportModel(string fileName)

GetBoolOption(System.String)¶

Get the current value of the specified boolean option.

Arguments: name (System.String) – Option name
Return type: System.Nullable<System.Boolean>
Returns: The option value, null if the specified option does not exist

public bool? GetBoolOption(string name)

GetConstraint(System.String)¶

Get the constraint with the corresponding name

Arguments: name (System.String) – Name of the constraint to be found
Return type: ampl.Entities.Constraint

public Constraint GetConstraint(string name)

GetConstraints()¶

Get the defined constraints

Return type: ampl.Entities.ConstraintMap

public ConstraintMap GetConstraints()

GetData(System.String[])¶

Get the data corresponding to the display statements. The statements can be AMPL expressions, or entities. It captures the equivalent of the command: <code>display ds1, …, dsn;</code> where<code> ds1, …, dsn </code>are the <code data-dev-comment-type=”paramref” class=”paramref”>statements</code> with which the function is called. As only one DataFrame is returned, the operation will fail if the results of the display statements cannot be indexed over the same set. As a result, any attempt to get data from more than one set, or to get data for multiple parameters with a different number of indexing sets will fail.

Arguments: statements (System.String<System.String>[]) – The display statements to be fetched
Return type: ampl.DataFrame
Returns: DataFrame capturing the output of the display command in tabular form

public DataFrame GetData(params string[] statements)

GetDblOption(System.String)¶

Get the current value of the specified option.

Arguments: name (System.String) – Option name
Return type: System.Nullable<System.Double>
Returns: The option value, null if the specified option does not exist

public double? GetDblOption(string name)

GetEntity(System.String)¶

Get entity corresponding to the specified name (looks for it in all types of entities)

Arguments: name (System.String) – Name of the entity
Return type: ampl.Entities.Entity
Returns: The AMPL entity with the specified name

public Entity GetEntity(string name)

GetIntOption(System.String)¶

Get the current value of the specified option.

Arguments: name (System.String) – Option name
Return type: System.Nullable<System.Int32>
Returns: The option value, null if the specified option does not exist

public int? GetIntOption(string name)

GetObjective(System.String)¶

Get the objective with the corresponding name

Arguments: name (System.String) – Name of the objective to be found
Return type: ampl.Entities.Objective

public Objective GetObjective(string name)

GetObjectives()¶

Get the defined objectives

Return type: ampl.Entities.ObjectiveMap

public ObjectiveMap GetObjectives()

GetOption(System.String)¶

Get the current value of the specified option.

Arguments: name (System.String) – Option name
Return type: System.String
Returns: The option value, null if the specified option does not exist

public string GetOption(string name)

GetOutput(System.String)¶

Equivalent to ampl.AMPL.eval but returns the output as a string.

Arguments: AMPLStatements (System.String) – A collection of AMPL statements and declarations to be passed to the interpreter
Return type: System.String

public string GetOutput(string AMPLStatements)

GetParameter(System.String)¶

Get the parameter with the corresponding name

Arguments: name (System.String) – Name of the parameter to be found
Return type: ampl.Entities.Parameter

public Parameter GetParameter(string name)

GetParameters()¶

Get the defined parameters

Return type: ampl.Entities.ParameterMap

public ParameterMap GetParameters()

GetSet(System.String)¶

Get the set with the corresponding name

Arguments: name (System.String) – Name of the set to be found
Return type: ampl.Entities.Set

public Set GetSet(string name)

GetSets()¶

Get the defined sets

Return type: ampl.Entities.SetMap

public SetMap GetSets()

GetValue(System.String)¶

Get a scalar value from the underlying AMPL interpreter, as a double or a string.

Arguments: scalarExpression (System.String) – An AMPL expression which evaluates to a scalar value.
Return type: ampl.Variant

public Variant GetValue(string scalarExpression)

GetVariable(System.String)¶

Get the variable with the corresponding name

Arguments: name (System.String) – Name of the variable to be found
Return type: ampl.Entities.Variable

public Variable GetVariable(string name)

GetVariables()¶

Get the defined variables

Return type: ampl.Entities.VariableMap

public VariableMap GetVariables()

Interrupt()¶

Interrupt an underlying asynchronous operation (execution of AMPL code by the AMPL interpreter). An asynchronous operation can be started via evalAsync(), solveAsync(), readAsync() and readDataAsync(). Does nothing if the engine and the solver are idle.

public void Interrupt()

Read(System.String)¶

Interprets the specified file (script or model or mixed) As a side effect, it invalidates all entities (as the passed file can contain any arbitrary command); the lists of entities will be re-populated lazily (at first access)

Arguments: filename (System.String) – Path to the file (Relative to the current working directory or absolute)

public void Read(string filename)

ReadAsync(System.String, System.Action)¶

Interprets the specified file asynchronously, interpreting it as a model or a script file. As a side effect, it invalidates all entities (as the passed file can contain any arbitrary command); the lists of entities will be re-populated lazily (at first access)

Arguments

filename (System.String) – Path to the file (Relative to the current working directory or absolute)
cb (System.Action) – Callback to be executed when the file has been interpreted

public void ReadAsync(string filename, Action cb)

ReadData(System.String)¶

Interprets the specified data file. As a side effect, it invalidates all entities (as the passed file can contain any arbitrary command); the lists of entities will be re-populated lazily (at first access)

Arguments: filename (System.String) – Path to the file (Relative to the current working directory or absolute)

public void ReadData(string filename)

ReadDataAsync(System.String, System.Action)¶

Interprets the specified data file asynchronously, interpreting it as a model or a script file. The file is interpreted as data. As a side effect, it invalidates all entities (as the file can contain arbitrary commands); the lists of entities will be re-populated lazily (at first access)

Arguments

filename (System.String) – Path to the file (Relative to the current working directory or absolute)
cb (System.Action) – Callback to be executed when the file has been interpreted

public void ReadDataAsync(string filename, Action cb)

ReadTable(System.String)¶

Read the table corresponding to the specified name, equivalent to the AMPL statement:

read table tableName;

Arguments: tableName (System.String) – Name of the table to be read

public void ReadTable(string tableName)

Reset()¶

Clears all entities in the underlying AMPL interpreter, clears all maps and invalidates all entities

public void Reset()

SetData(ampl.DataFrame, System.String)¶

Assign the data in the dataframe to the AMPL entities with the names corresponding to the column names.If setName is null, only the parameters value will be assigned.

Arguments

df (ampl.DataFrame) – The dataframe containing the data to be assigned
setName (System.String) – The name of the set to which the indices values of the DataFrame are to be assigned.

public void SetData(DataFrame df, string setName = null)

SetOption(System.String, System.Boolean)¶

Set an AMPL option to a specified boolean value. In AMPL, boolean options are represented as integer: 0 for false, 1 for true.

Arguments

name (System.String) – Name of the option to be set (alphanumeric without spaces)
value (System.Boolean) – Value the option must be set to

public void SetOption(string name, bool value)

SetOption(System.String, System.Double)

Set an AMPL option to a specified double value.

Arguments

name (System.String) – Name of the option to be set (alphanumeric without spaces)
value (System.Double) – Value the option must be set to

public void SetOption(string name, double value)

SetOption(System.String, System.Int32)

Set an AMPL option to a specified integer value.

Arguments

name (System.String) – Name of the option to be set (alphanumeric without spaces)
value (System.Int32) – Value the option must be set to

public void SetOption(string name, int value)

SetOption(System.String, System.String)

Set an AMPL option to a specified value.

Arguments

name (System.String) – Name of the option to be set (alphanumeric without spaces)
value (System.String) – String representing the value the option must be set to

public void SetOption(string name, string value)

Show(ampl.Entities.Entity[])¶

public void Show(params Entity[] entities)

Solve()¶

Solve the current model

public void Solve()

SolveAsync(System.Action)¶

Solve the current model asynchronously

Arguments: cb (System.Action) – Call back to be executed when completed

public void SolveAsync(Action cb)

ToString()¶

Get a string describing the object. Returns the version of the API and either the version of the interpreter or the message "AMPL is not running" if the interpreter is not running (e.g. due to unexpected internal error or to a call AMPL.Close())

Return type: System.String

public override string ToString()

Properties ¶

ampl.AMPL.CurrentObjectiveName¶

Get the name of the currently active objective (see the objective command), or null if no objective has been declared or selected

Return type: System.String

public string CurrentObjectiveName { get; }

Events ¶

Error()¶

Raised for each AMPL error, if ampl.AMPL.EnableErrorAndWarningRouting has been called on the current object instance

Return type: System.Action<AMPLException>

public event Action<AMPLException> Error

Output()¶

Raised for each AMPL output, if ampl.AMPL.EnableOutputRouting has been called on the current object instance

Return type: System.Action<Kind>

public event Action<Kind, string> Output

Warning()¶

Raised for each AMPL warning, if ampl.AMPL.EnableErrorAndWarningRouting has been called on the current object instance

Return type: System.Action<AMPLException>

public event Action<AMPLException> Warning

AMPL Class¶

Inheritance Hierarchy¶

Syntax¶

Constructors¶

Methods¶

Properties¶

Events¶

Inheritance Hierarchy ¶

Syntax ¶

Constructors ¶

Methods ¶

Properties ¶

Events ¶