Class: Digiproc::Probability::RandomBitGenerator

Inherits:
Object
  • Object
show all
Defined in:
lib/probability/bit_generator.rb

Overview

Create random bit for testing purposes

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(bits_per_symbol:, p_0: 0.5, p_1: 0.5) ⇒ RandomBitGenerator

Arguments

# bits_per_symbol
Integer

set the number of bits for each symbol

p_0
Float

between 0 and 1: probability of a 0 bit (defaults to 0.5)

p_1
Float

between 0 and 1: probability of a 1 bit (defaults to 0.5)

bitstream = bitgen.new(bits_per_symbol: 1) => same as bitgen.new_bitstream

Raises:

  • (ArgumentError) 


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# File 'lib/probability/bit_generator.rb', line 69

def initialize(bits_per_symbol: , p_0: 0.5, p_1: 0.5 )
    raise ArgumentError.new("Probabilities of bits must add up to 1") if p_0 + p_1 != 1
    @bits_per_symbol, @p_0, @p_1, @random_generator = bits_per_symbol, p_0, p_1, Random.new
end

Instance Attribute Details

#bits_per_symbol ⇒ Object

Returns the value of attribute bits_per_symbol.



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# File 'lib/probability/bit_generator.rb', line 60

def bits_per_symbol
  @bits_per_symbol
end

#p_0 ⇒ Object

Returns the value of attribute p_0.



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# File 'lib/probability/bit_generator.rb', line 60

def p_0
  @p_0
end

#p_1 ⇒ Object

Returns the value of attribute p_1.



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# File 'lib/probability/bit_generator.rb', line 60

def p_1
  @p_1
end

#random_generator ⇒ Object

Returns the value of attribute random_generator.



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# File 'lib/probability/bit_generator.rb', line 60

def random_generator
  @random_generator
end

Class Method Details

.bitstream(size:, p_0: 0.5, p_1: 0.5, random_generator: Random.new) ⇒ Object

Returns a string representing a bitstream

Arguments

size
Integer

number of desired bits

p_0
Float

(between 0 and 1) probability of a bit 0 occurring (default value: 0.5)

p_1
Float

(between 0 and 1) probability of a bit 1 occurring (default value: 0.5)

random_generator

Any random generator that follows the prototype of ruby’s ‘Random` class. Defaults to `Random.new`

bitgen = Digiproc::Probability::RandomBitGenerator bitgen.bitstream(size: 10) # => “1000010010”



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# File 'lib/probability/bit_generator.rb', line 16

def self.bitstream(size: , p_0: 0.5, p_1: 0.5, random_generator: Random.new)
    stream = ''
    size.times do 
        stream += get_bit(p_0: p_0, p_1: p_1, random_generator: random_generator).to_s
    end
    stream
end

.get_bit(p_0: 0.5, p_1: 0.5, random_generator: Random.new) ⇒ Object

Returns an Integer

Arguments

p_0
Float

(between 0 and 1) probability of a bit 0 occurring (default value: 0.5)

p_1
Float

(between 0 and 1) probability of a bit 1 occurring (default value: 0.5)

random_generator

Any random generator that follows the prototype of ruby’s ‘Random` class. Defaults to `Random.new`

bitgen.bitstream # => 1

Raises:

  • (ArgumentError) 


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# File 'lib/probability/bit_generator.rb', line 32

def self.get_bit(p_0: 0.5, p_1: 0.5, random_generator: Random.new)
    raise ArgumentError.new("Probabilities must add up to 1") if p_0 + p_1 != 1
    rnum = 1 - random_generator.rand
    return 0 if rnum <= p_0 
    return 1
end

.new_bitstream(p_0: 0.5, p_1: 0.5) ⇒ Object

Constructor for bitstream

Arguments

p_0
Float

between 0 and 1: probability of a 0 bit (defaults to 0.5)

p_1
Float

between 0 and 1: probability of a 1 bit (defaults to 0.5)

bitstream = bitgen.new_bitstream



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# File 'lib/probability/bit_generator.rb', line 45

def self.new_bitstream(p_0: 0.5 , p_1: 0.5)
    self.new(bits_per_symbol: 1, p_0: p_0, p_1: p_1)
end

.new_symbol_stream(bits_per_symbol:, p_0: 0.5, p_1: 0.5) ⇒ Object

Constructor for symbol_stream

Arguments

bits_per_symbol
Integer

set the number of bits for each symbol

p_0
Float

between 0 and 1: probability of a 0 bit (defaults to 0.5)

p_1
Float

between 0 and 1: probability of a 1 bit (defaults to 0.5)

bitstream = bitgen.new_bitstream



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# File 'lib/probability/bit_generator.rb', line 56

def self.new_symbol_stream(bits_per_symbol: , p_0: 0.5, p_1: 0.5)
    self.new(bits_per_symbol: bits_per_symbol, p_0: p_0, p_1: p_1) 
end

Instance Method Details

#generate(size) ⇒ Object

Arguments

size
Integer

number of symbols to be generated (or bits if self.bits_per_symbol is 1)

bistream = Digiproc::Probability::RandomBitGenerator.new_bitstream symstream = Digiproc::Probability::RandomBitGenerator.new_symbol_stream(bits_per_symbol: 8) bitstream.generate(10) # => “0001110010” symstream.generate(4) # => [“10100111”, “00111100”, “00111010”, “10000100”]



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# File 'lib/probability/bit_generator.rb', line 81

def generate(size)
    if self.bits_per_symbol == 1
        return self.class.bitstream(size: size, p_0: @p_0, p_1: @p_1, random_generator: @random_generator)
    else
        signal = []
        size.times do 
            signal << self.class.bitstream(size: @bits_per_symbol, p_0: @p_0, p_1: @p_1, random_generator: @random_generator)
        end
        return signal
    end
end