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ns3::ZipfRandomVariable Class Reference

The Zipf distribution Random Number Generator (RNG) that allows stream numbers to be set deterministically. More...

#include <random-variable-stream.h>

+ Inheritance diagram for ns3::ZipfRandomVariable:

Public Member Functions

 ZipfRandomVariable ()
 Creates a Zipf distribution RNG with the default values for n and alpha.
 
double GetAlpha (void) const
 Returns the alpha value for the Zipf distribution returned by this RNG stream. More...
 
uint32_t GetInteger (uint32_t n, uint32_t alpha)
 Returns a random unsigned integer from a Zipf distribution with the specified n and alpha. More...
 
virtual uint32_t GetInteger (void)
 Returns a random unsigned integer from a Zipf distribution with the current n and alpha. More...
 
uint32_t GetN (void) const
 Returns the n value for the Zipf distribution returned by this RNG stream. More...
 
double GetValue (uint32_t n, double alpha)
 Returns a random double from a Zipf distribution with the specified n and alpha. More...
 
virtual double GetValue (void)
 Returns a random double from a Zipf distribution with the current n and alpha. More...
 
- Public Member Functions inherited from ns3::RandomVariableStream
int64_t GetStream (void) const
 Returns the stream number for this RNG stream. More...
 
bool IsAntithetic (void) const
 Returns true if antithetic values should be generated. More...
 
void SetAntithetic (bool isAntithetic)
 Specifies whether antithetic values should be generated. More...
 
void SetStream (int64_t stream)
 Specifies the stream number for this RNG stream. More...
 
- Public Member Functions inherited from ns3::Object
void AggregateObject (Ptr< Object > other)
 
void Dispose (void)
 
AggregateIterator GetAggregateIterator (void) const
 
virtual TypeId GetInstanceTypeId (void) const
 
template<typename T >
Ptr< T > GetObject (void) const
 
template<typename T >
Ptr< T > GetObject (TypeId tid) const
 
void Initialize (void)
 
- Public Member Functions inherited from ns3::SimpleRefCount< Object, ObjectBase, ObjectDeleter >
 SimpleRefCount (const SimpleRefCount &o)
 
uint32_t GetReferenceCount (void) const
 
SimpleRefCountoperator= (const SimpleRefCount &o)
 
void Ref (void) const
 
void Unref (void) const
 
- Public Member Functions inherited from ns3::ObjectBase
void GetAttribute (std::string name, AttributeValue &value) const
 
bool GetAttributeFailSafe (std::string name, AttributeValue &attribute) const
 
void SetAttribute (std::string name, const AttributeValue &value)
 
bool SetAttributeFailSafe (std::string name, const AttributeValue &value)
 
bool TraceConnect (std::string name, std::string context, const CallbackBase &cb)
 
bool TraceConnectWithoutContext (std::string name, const CallbackBase &cb)
 
bool TraceDisconnect (std::string name, std::string context, const CallbackBase &cb)
 
bool TraceDisconnectWithoutContext (std::string name, const CallbackBase &cb)
 

Static Public Member Functions

static TypeId GetTypeId (void)
 
- Static Public Member Functions inherited from ns3::RandomVariableStream
static TypeId GetTypeId (void)
 
- Static Public Member Functions inherited from ns3::Object
static TypeId GetTypeId (void)
 
- Static Public Member Functions inherited from ns3::SimpleRefCount< Object, ObjectBase, ObjectDeleter >
static void Cleanup (void)
 
- Static Public Member Functions inherited from ns3::ObjectBase
static TypeId GetTypeId (void)
 

Private Attributes

double m_alpha
 The alpha value for the Zipf distribution returned by this RNG stream.
 
double m_c
 The normalization constant.
 
uint32_t m_n
 The n value for the Zipf distribution returned by this RNG stream.
 

Additional Inherited Members

- Protected Member Functions inherited from ns3::RandomVariableStream
RngStreamPeek (void) const
 Returns a pointer to the underlying RNG stream.
 
- Protected Member Functions inherited from ns3::Object
 Object (const Object &o)
 
virtual void DoDispose (void)
 
virtual void DoInitialize (void)
 
virtual void NotifyNewAggregate (void)
 
- Protected Member Functions inherited from ns3::ObjectBase
void ConstructSelf (const AttributeConstructionList &attributes)
 
virtual void NotifyConstructionCompleted (void)
 

Detailed Description

The Zipf distribution Random Number Generator (RNG) that allows stream numbers to be set deterministically.

This class supports the creation of objects that return random numbers from a fixed Zipf distribution. It also supports the generation of single random numbers from various Zipf distributions.

The Zipf's law states that given some corpus of natural language utterances, the frequency of any word is inversely proportional to its rank in the frequency table.

Zipf's distribution has two parameters, alpha and N, where: $ \alpha > 0 $ (real) and $ N \in \{1,2,3 \dots\}$ (integer). Probability Mass Function is $ f(k; \alpha, N) = k^{-\alpha}/ H_{N,\alpha} $ where $ H_{N,\alpha} = \sum_{m=1}^N m^{-\alpha} $

Here is an example of how to use this class:

uint32_t n = 1;
double alpha = 2.0;
Ptr<ZipfRandomVariable> x = CreateObject<ZipfRandomVariable> ();
x->SetAttribute ("N", IntegerValue (n));
x->SetAttribute ("Alpha", DoubleValue (alpha));
// The expected value for the mean of the values returned by a
// Zipfly distributed random variable is equal to
//
// H
// N, alpha - 1
// E[value] = ---------------
// H
// N, alpha
//
// where
//
// N
// ---
// \ -alpha
// H = / m .
// N, alpha ---
// m=1
//
// For this test,
//
// -(alpha - 1)
// 1
// E[value] = ---------------
// -alpha
// 1
//
// = 1 .
//
double value = x->GetValue ();

Config Paths

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

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

Attributes

  • N: The n value for the Zipf distribution returned by this RNG stream.
  • Alpha: The alpha value for the Zipf distribution returned by this RNG stream.
    • Set with class: ns3::DoubleValue
    • Underlying type: double -1.79769e+308:1.79769e+308
    • Initial value: 0
    • Flags: construct write read

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.

Definition at line 2049 of file random-variable-stream.h.

Member Function Documentation

double ns3::ZipfRandomVariable::GetAlpha ( void  ) const

Returns the alpha value for the Zipf distribution returned by this RNG stream.

Returns
The alpha value for the Zipf distribution returned by this RNG stream.

Definition at line 1277 of file random-variable-stream.cc.

References m_alpha, and NS_LOG_FUNCTION.

uint32_t ns3::ZipfRandomVariable::GetInteger ( uint32_t  n,
uint32_t  alpha 
)

Returns a random unsigned integer from a Zipf distribution with the specified n and alpha.

Parameters
nN value for the Zipf distribution.
alphaAlpha value for the Zipf distribution.
Returns
A random unsigned integer value.

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.

Definition at line 1316 of file random-variable-stream.cc.

References GetValue(), and NS_LOG_FUNCTION.

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

Returns a random unsigned integer from a Zipf distribution with the current n and alpha.

Returns
A random unsigned integer value.

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 1329 of file random-variable-stream.cc.

References GetValue(), m_alpha, m_n, and NS_LOG_FUNCTION.

uint32_t ns3::ZipfRandomVariable::GetN ( void  ) const

Returns the n value for the Zipf distribution returned by this RNG stream.

Returns
The n value for the Zipf distribution returned by this RNG stream.

Definition at line 1271 of file random-variable-stream.cc.

References m_n, and NS_LOG_FUNCTION.

double ns3::ZipfRandomVariable::GetValue ( uint32_t  n,
double  alpha 
)

Returns a random double from a Zipf distribution with the specified n and alpha.

Parameters
nN value for the Zipf distribution.
alphaAlpha value for the Zipf distribution.
Returns
A floating point random value.

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.

Definition at line 1284 of file random-variable-stream.cc.

References ns3::RandomVariableStream::IsAntithetic(), m_alpha, m_c, m_n, NS_LOG_FUNCTION, ns3::RandomVariableStream::Peek(), and ns3::RngStream::RandU01().

Referenced by RandomVariableStreamZipfTestCase::DoRun(), and RandomVariableStreamZipfAntitheticTestCase::DoRun().

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

Returns a random double from a Zipf distribution with the current n and alpha.

Returns
A floating point random value.

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.

Note that we have to re-implement this method here because the method is overloaded above for the two-argument variant and the c++ name resolution rules don't work well with overloads split between parent and child classes.

Implements ns3::RandomVariableStream.

Definition at line 1323 of file random-variable-stream.cc.

References m_alpha, m_n, and NS_LOG_FUNCTION.

Referenced by GetInteger().


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