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@antirez
Created January 19, 2010 15:24
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# Power law (log tail) distribution
# Copyright(C) 2010 Salvatore Sanfilippo
# this code is under the public domain
# min and max are both inclusive
# n is the distribution power: the higher, the more biased
def powerlaw(min,max,n)
max += 1
pl = ((max**(n+1) - min**(n+1))*rand() + min**(n+1))**(1.0/(n+1))
(max-1-pl.to_i)+min
end
freq = {}
100000.times {
n = powerlaw(30,80,2).to_i
freq[n] = 0 if !freq[n]
freq[n] += 1
}
(0..100).each{|x|
puts "#{x} => #{freq[x]}"
}
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