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ns3::EmpiricalRandomVariable Class Reference
Core » Random Variables

The Random Number Generator (RNG) that has a specified empirical distribution. More...

#include "random-variable-stream.h"

+ Inheritance diagram for ns3::EmpiricalRandomVariable:
+ Collaboration diagram for ns3::EmpiricalRandomVariable:

Classes

class  ValueCDF
 Helper to hold one point of the CDF. More...
 

Public Member Functions

 EmpiricalRandomVariable ()
 Creates an empirical RNG that has a specified, empirical distribution. More...
 
void CDF (double v, double c)
 Specifies a point in the empirical distribution. More...
 
virtual uint32_t GetInteger (void)
 Returns the next value in the empirical distribution. More...
 
virtual double GetValue (void)
 Returns the next value in the empirical distribution. More...
 
- Public Member Functions inherited from ns3::RandomVariableStream
 RandomVariableStream ()
 Default constructor. More...
 
virtual ~RandomVariableStream ()
 Destructor. More...
 
int64_t GetStream (void) const
 Returns the stream number for the RngStream. More...
 
bool IsAntithetic (void) const
 Check if antithetic values will be generated. More...
 
void SetAntithetic (bool isAntithetic)
 Specify whether antithetic values should be generated. More...
 
void SetStream (int64_t stream)
 Specifies the stream number for the RngStream. More...
 
- Public Member Functions inherited from ns3::Object
 Object ()
 Constructor. More...
 
virtual ~Object ()
 Destructor. More...
 
void AggregateObject (Ptr< Object > other)
 Aggregate two Objects together. More...
 
void Dispose (void)
 Dispose of this Object. More...
 
AggregateIterator GetAggregateIterator (void) const
 Get an iterator to the Objects aggregated to this one. More...
 
virtual TypeId GetInstanceTypeId (void) const
 Get the most derived TypeId for this Object. More...
 
template<typename T >
Ptr< T > GetObject (void) const
 Get a pointer to the requested aggregated Object. More...
 
template<typename T >
Ptr< T > GetObject (TypeId tid) const
 Get a pointer to the requested aggregated Object by TypeId. More...
 
void Initialize (void)
 Invoke DoInitialize on all Objects aggregated to this one. More...
 
bool IsInitialized (void) const
 Check if the object has been initialized. More...
 
- Public Member Functions inherited from ns3::SimpleRefCount< Object, ObjectBase, ObjectDeleter >
 SimpleRefCount ()
 Default constructor. More...
 
 SimpleRefCount (const SimpleRefCount &o)
 Copy constructor. More...
 
uint32_t GetReferenceCount (void) const
 Get the reference count of the object. More...
 
SimpleRefCount & operator= (const SimpleRefCount &o)
 Assignment operator. More...
 
void Ref (void) const
 Increment the reference count. More...
 
void Unref (void) const
 Decrement the reference count. More...
 
- Public Member Functions inherited from ns3::ObjectBase
virtual ~ObjectBase ()
 Virtual destructor. More...
 
void GetAttribute (std::string name, AttributeValue &value) const
 Get the value of an attribute, raising fatal errors if unsuccessful. More...
 
bool GetAttributeFailSafe (std::string name, AttributeValue &value) const
 Get the value of an attribute without raising erros. More...
 
void SetAttribute (std::string name, const AttributeValue &value)
 Set a single attribute, raising fatal errors if unsuccessful. More...
 
bool SetAttributeFailSafe (std::string name, const AttributeValue &value)
 Set a single attribute without raising errors. More...
 
bool TraceConnect (std::string name, std::string context, const CallbackBase &cb)
 Connect a TraceSource to a Callback with a context. More...
 
bool TraceConnectWithoutContext (std::string name, const CallbackBase &cb)
 Connect a TraceSource to a Callback without a context. More...
 
bool TraceDisconnect (std::string name, std::string context, const CallbackBase &cb)
 Disconnect from a TraceSource a Callback previously connected with a context. More...
 
bool TraceDisconnectWithoutContext (std::string name, const CallbackBase &cb)
 Disconnect from a TraceSource a Callback previously connected without a context. More...
 

Static Public Member Functions

static TypeId GetTypeId (void)
 Register this type. More...
 
- Static Public Member Functions inherited from ns3::RandomVariableStream
static TypeId GetTypeId (void)
 Register this type. More...
 
- Static Public Member Functions inherited from ns3::Object
static TypeId GetTypeId (void)
 Register this type. More...
 
- Static Public Member Functions inherited from ns3::ObjectBase
static TypeId GetTypeId (void)
 Get the type ID. More...
 

Private Member Functions

virtual double Interpolate (double c1, double c2, double v1, double v2, double r)
 Linear nterpolation between two points on the CDF to estimate the value at r. More...
 
virtual void Validate ()
 Check that the CDF is valid. More...
 

Private Attributes

std::vector< ValueCDF > m_emp
 The vector of CDF points. More...
 
bool m_validated
 true once the CDF has been validated. More...
 

Additional Inherited Members

- Protected Member Functions inherited from ns3::RandomVariableStream
RngStream * Peek (void) const
 Get the pointer to the underlying RngStream. More...
 
- Protected Member Functions inherited from ns3::Object
 Object (const Object &o)
 Copy an Object. More...
 
virtual void DoDispose (void)
 Destructor implementation. More...
 
virtual void DoInitialize (void)
 Initialize() implementation. More...
 
virtual void NotifyNewAggregate (void)
 Notify all Objects aggregated to this one of a new Object being aggregated. More...
 
- Protected Member Functions inherited from ns3::ObjectBase
void ConstructSelf (const AttributeConstructionList &attributes)
 Complete construction of ObjectBase; invoked by derived classes. More...
 
virtual void NotifyConstructionCompleted (void)
 Notifier called once the ObjectBase is fully constructed. More...
 
- Related Functions inherited from ns3::ObjectBase
static TypeId GetObjectIid (void)
 Ensure the TypeId for ObjectBase gets fully configured to anchor the inheritance tree properly. More...
 

Detailed Description

The Random Number Generator (RNG) that has a specified empirical distribution.

Defines a random variable that has a specified, empirical distribution. The distribution is specified by a series of calls to the CDF member function, specifying a value and the probability that the function value is less than the specified value. When values are requested, a uniform random variable is used to select a probability, and the return value is interpreted linearly between the two appropriate points in the CDF. The method is known as inverse transform sampling: (http://en.wikipedia.org/wiki/Inverse_transform_sampling).

Here is an example of how to use this class:

// Create the RNG with a uniform distribution between 0 and 10.
Ptr<EmpiricalRandomVariable> x = CreateObject<EmpiricalRandomVariable> ();
x->CDF ( 0.0, 0.0);
x->CDF ( 5.0, 0.5);
x->CDF (10.0, 1.0);
// The expected value for the mean of the values returned by this
// empirical distribution is the midpoint of the distribution
//
// E[value] = 5 .
//
double value = x->GetValue ();

Config Paths

ns3::EmpiricalRandomVariable is accessible through the following paths with Config::Set and Config::Connect:

  • "/NodeList/[i]/DeviceList/[i]/$ns3::SimpleNetDevice/ReceiveErrorModel/$ns3::RateErrorModel/RanVar/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/DeviceList/[i]/$ns3::SimpleNetDevice/ReceiveErrorModel/$ns3::BurstErrorModel/BurstStart/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/DeviceList/[i]/$ns3::SimpleNetDevice/ReceiveErrorModel/$ns3::BurstErrorModel/BurstSize/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/DeviceList/[i]/$ns3::CsmaNetDevice/ReceiveErrorModel/$ns3::RateErrorModel/RanVar/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/DeviceList/[i]/$ns3::CsmaNetDevice/ReceiveErrorModel/$ns3::BurstErrorModel/BurstStart/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/DeviceList/[i]/$ns3::CsmaNetDevice/ReceiveErrorModel/$ns3::BurstErrorModel/BurstSize/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/DeviceList/[i]/$ns3::PointToPointNetDevice/ReceiveErrorModel/$ns3::RateErrorModel/RanVar/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/DeviceList/[i]/$ns3::PointToPointNetDevice/ReceiveErrorModel/$ns3::BurstErrorModel/BurstStart/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/DeviceList/[i]/$ns3::PointToPointNetDevice/ReceiveErrorModel/$ns3::BurstErrorModel/BurstSize/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/DeviceList/[i]/$ns3::WifiNetDevice/Channel/$ns3::YansWifiChannel/PropagationLossModel/$ns3::RandomPropagationLossModel/Variable/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/DeviceList/[i]/$ns3::WifiNetDevice/Channel/$ns3::YansWifiChannel/PropagationDelayModel/$ns3::RandomPropagationDelayModel/Variable/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/DeviceList/[i]/$ns3::WaveNetDevice/Channel/$ns3::YansWifiChannel/PropagationLossModel/$ns3::RandomPropagationLossModel/Variable/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/DeviceList/[i]/$ns3::WaveNetDevice/Channel/$ns3::YansWifiChannel/PropagationDelayModel/$ns3::RandomPropagationDelayModel/Variable/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/ApplicationList/[i]/$ns3::DhcpClient/Transactions/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/ApplicationList/[i]/$ns3::OnOffApplication/OnTime/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/ApplicationList/[i]/$ns3::OnOffApplication/OffTime/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::GaussMarkovMobilityModel/MeanVelocity/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::GaussMarkovMobilityModel/MeanDirection/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::GaussMarkovMobilityModel/MeanPitch/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomDirection2dMobilityModel/Speed/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomDirection2dMobilityModel/Pause/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomWalk2dMobilityModel/Direction/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomWalk2dMobilityModel/Speed/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomWaypointMobilityModel/Speed/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomWaypointMobilityModel/Pause/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomWaypointMobilityModel/PositionAllocator/$ns3::RandomRectanglePositionAllocator/X/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomWaypointMobilityModel/PositionAllocator/$ns3::RandomRectanglePositionAllocator/Y/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomWaypointMobilityModel/PositionAllocator/$ns3::RandomBoxPositionAllocator/X/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomWaypointMobilityModel/PositionAllocator/$ns3::RandomBoxPositionAllocator/Y/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomWaypointMobilityModel/PositionAllocator/$ns3::RandomBoxPositionAllocator/Z/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomWaypointMobilityModel/PositionAllocator/$ns3::RandomDiscPositionAllocator/Theta/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::MobilityModel/$ns3::RandomWaypointMobilityModel/PositionAllocator/$ns3::RandomDiscPositionAllocator/Rho/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::ArpL3Protocol/RequestJitter/$ns3::EmpiricalRandomVariable"
  • "/NodeList/[i]/$ns3::Icmpv6L4Protocol/SolicitationJitter/$ns3::EmpiricalRandomVariable"
  • "/ChannelList/[i]/$ns3::YansWifiChannel/PropagationLossModel/$ns3::RandomPropagationLossModel/Variable/$ns3::EmpiricalRandomVariable"
  • "/ChannelList/[i]/$ns3::YansWifiChannel/PropagationDelayModel/$ns3::RandomPropagationDelayModel/Variable/$ns3::EmpiricalRandomVariable"

No Attributes are defined for this type.

Attributes defined in parent class ns3::RandomVariableStream

  • Stream: The stream number for this RNG stream. -1 means "allocate a stream automatically". Note that if -1 is set, Get will return -1 so that it is not possible to know which value was automatically allocated.
    • Set with class: ns3::IntegerValue
    • Underlying type: int64_t -9223372036854775808:9223372036854775807
    • Initial value: -1
    • Flags: construct write read
  • Antithetic: Set this RNG stream to generate antithetic values
    • Set with class: BooleanValue
    • Underlying type: bool
    • Initial value: false
    • Flags: construct write read

No TraceSources are defined for this type.
Size of this type is 88 bytes (on a 64-bit architecture).

Definition at line 2442 of file random-variable-stream.h.

Constructor & Destructor Documentation

ns3::EmpiricalRandomVariable::EmpiricalRandomVariable ( )

Creates an empirical RNG that has a specified, empirical distribution.

Definition at line 1566 of file random-variable-stream.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

void ns3::EmpiricalRandomVariable::CDF ( double  v,
double  c 
)

Specifies a point in the empirical distribution.

Parameters
[in]vThe function value for this point
[in]cProbability that the function is less than or equal to v

Definition at line 1630 of file random-variable-stream.cc.

References m_emp, and NS_LOG_FUNCTION.

Referenced by RandomVariableStreamEmpiricalTestCase::DoRun(), and RandomVariableStreamEmpiricalAntitheticTestCase::DoRun().

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uint32_t ns3::EmpiricalRandomVariable::GetInteger ( void  )
virtual

Returns the next value in the empirical distribution.

Returns
The integer next value in the empirical distribution.

Note that antithetic values are being generated if m_isAntithetic is equal to true. If $u$ is a uniform variable over [0,1] and $x$ is a value that would be returned normally, then $(1 - u$) is the distance that $u$ would be from $1$. The value returned in the antithetic case, $x'$, uses (1-u), which is the distance $u$ is from the 1.

Implements ns3::RandomVariableStream.

Definition at line 1624 of file random-variable-stream.cc.

References GetValue(), and NS_LOG_FUNCTION.

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TypeId ns3::EmpiricalRandomVariable::GetTypeId ( void  )
static

Register this type.

Returns
The object TypeId.

Definition at line 1557 of file random-variable-stream.cc.

References ns3::TypeId::SetParent().

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double ns3::EmpiricalRandomVariable::GetValue ( void  )
virtual

Returns the next value in the empirical distribution.

Returns
The floating point next value in the empirical distribution.

Note that antithetic values are being generated if m_isAntithetic is equal to true. If $u$ is a uniform variable over [0,1] and $x$ is a value that would be returned normally, then $(1 - u$) is the distance that $u$ would be from $1$. The value returned in the antithetic case, $x'$, uses (1-u), which is the distance $u$ is from the 1.

Implements ns3::RandomVariableStream.

Definition at line 1574 of file random-variable-stream.cc.

References Interpolate(), ns3::RandomVariableStream::IsAntithetic(), m_emp, m_validated, NS_LOG_FUNCTION, ns3::RandomVariableStream::Peek(), ns3::RngStream::RandU01(), and Validate().

Referenced by RandomVariableStreamEmpiricalTestCase::DoRun(), RandomVariableStreamEmpiricalAntitheticTestCase::DoRun(), and GetInteger().

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double ns3::EmpiricalRandomVariable::Interpolate ( double  c1,
double  c2,
double  v1,
double  v2,
double  r 
)
privatevirtual

Linear nterpolation between two points on the CDF to estimate the value at r.

Parameters
[in]c1The first argument value.
[in]c2The secong argument value.
[in]v1The first CDF value.
[in]v2The secong CDF value.
[in]rThe argument value to interpolate to.
Returns
The interpolated CDF at r.

Definition at line 1666 of file random-variable-stream.cc.

References NS_LOG_FUNCTION.

Referenced by GetValue().

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void ns3::EmpiricalRandomVariable::Validate ( )
privatevirtual

Check that the CDF is valid.

A valid CDF has

  • Strictly increasing arguments, and
  • Strictly increasing CDF.

It is a fatal error to fail validation.

Definition at line 1637 of file random-variable-stream.cc.

References ns3::EmpiricalRandomVariable::ValueCDF::cdf, m_emp, m_validated, NS_FATAL_ERROR, NS_LOG_FUNCTION, and ns3::EmpiricalRandomVariable::ValueCDF::value.

Referenced by GetValue().

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Member Data Documentation

std::vector<ValueCDF> ns3::EmpiricalRandomVariable::m_emp
private

The vector of CDF points.

Definition at line 2544 of file random-variable-stream.h.

Referenced by CDF(), GetValue(), and Validate().

bool ns3::EmpiricalRandomVariable::m_validated
private

true once the CDF has been validated.

Definition at line 2542 of file random-variable-stream.h.

Referenced by GetValue(), and Validate().

The documentation for this class was generated from the following files: