Entity Class

An AMPL entity such as a parameter or a variable.

An entity can either represent a single instance of an AMPL algebraic entity or, if the corresponding declaration has an indexing expression, a mapping from keys to instances.In the derived classes, it has methods to access instance-level properties which can be used in case the represented entity is scalar. To gain access to all the values in an entity (for all instances and all suffixes for that entities), use the function ampl.Entities.Entity.GetValues(). The algebraic entities which currenty have an equivalent class in the API are:

Variables (see ampl.Entities.Variable)

Constraints (see ampl.Entities.Constraint)

Objectives (see ampl.Entities.Objective)

Sets (see ampl.Entities.Set)

Parameters (see ampl.Entities.Parameter)

Namespace

ampl.Entities

Assemblies

  • AMPL

Inheritance Hierarchy

Syntax

public class Entity : IEnumerable
class ampl.Entities.Entity

Methods

GetEnumerator()
Return type

System.Collections.IEnumerator

public virtual IEnumerator GetEnumerator()
GetValues()

Get the principal values of this entity as a DataFrame. The specific returned value depends on the type of entity(see list below).

For:

  • Variables and Objectives it returns the suffix val

  • Parameters it returns their values

  • Constraints it returns the suffix dual

  • Sets it returns all the members of the set, Note that it does not apply to indexed sets. See ampl.SetInstance.GetValues

Return type

ampl.DataFrame

Returns

A DataFrame containing the values for all instances

public virtual DataFrame GetValues()
GetValues(System.String[])

Get the specified suffixes value for all instances in a DataFrame

Arguments

suffixes (System.String<System.String>[]) – Suffixes to get

Return type

ampl.DataFrame

Returns

A DataFrame containing the specified values

public DataFrame GetValues(params string[] suffixes)
SetValues(ampl.DataFrame)

Set the values of this entiy to the correponding values of a DataFrame indexed over the same sets(or a subset). This function assigns the values in the first data column of the passed dataframe to the entity the function is called from. In particular, the statement:

`x.SetValues(y.GetValues());`

is semantically equivalent to the AMPL statement:

`let { s in S } x[s] := y[s];`
Arguments

data (ampl.DataFrame) – The data to set the entity to

public void SetValues(DataFrame data)
ToString()

Returns a textual representation of this entity

Return type

System.String

public override string ToString()

Properties

ampl.Entities.Entity.Indexarity

Get the indexarity of this entity (sum of the dimensions of the indexing sets). This value indicates the arity of the tuple to be passed to the method ampl.Entities.Entity.Get in order to access an instance of this entity. See the following AMPL examples:

var x;               # indexarity = 0
var y {1..2};        # indexarity = 1
var z {1..2,3..4};   # indexarity = 2
var zz {{ (1, 2)} };   # indexarity = 2

Get the sum of the dimensions of the indexing sets or 0 if the entity is not indexed

Return type

System.Int32

public int Indexarity { get; }
ampl.Entities.Entity.IndexingSets

Get the AMPL string representation of the sets on which this entity is indexed.The obtained vector can be modified without any effect to the entity. Is equal to the string representation of the indexing sets for this entity or an empty array if the entity is scalar

Return type

System.String<System.String>[]

public string[] IndexingSets { get; }
ampl.Entities.Entity.IsScalar

Check whether this entity is scalar. Equivalent to testing whether indexarity is equal to zero, is true if the entity is scalar (not indexed over any set)

Return type

System.Boolean

public bool IsScalar { get; }
ampl.Entities.Entity.Name

Get the name of this entity

Return type

System.String

public string Name { get; }
ampl.Entities.Entity.NumInstances

Get the number of instances in this entity

Return type

System.Int32

public int NumInstances { get; }
ampl.Entities.Entity.XRef

Get the names of all entities which depend on this one.

Return type

System.String<System.String>[]

public string[] XRef { get; }