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class Node | |
attr_accessor :name, :prob, :children, :code | |
def initialize name, prob, children = [], code = nil | |
@name = name | |
@prob = prob | |
@children = children | |
@code = code | |
end | |
end | |
def make_bin_tree queue | |
while queue.size > 1 | |
queue.sort_by!{|e| -e.prob} | |
right = queue.pop | |
left = queue.pop | |
queue.push(Node.new("(#{left.name},#{right.name})", left.prob + right.prob, [left, right]) ) | |
end | |
queue | |
end | |
def huffmanize tree | |
list = [] | |
dfs = -> (sub_tree, code, depth) { | |
if sub_tree.children == [] | |
sub_tree.code = code | |
list << sub_tree | |
else | |
sub_tree.children.each_with_index{ |e, i| | |
dfs.(e, code + i.to_s , depth + 1) | |
} | |
end | |
} | |
dfs.(tree[0], "", 0) | |
list.sort_by{|e| e.name} | |
end | |
def print_huffman huf | |
huf.each{ |e| | |
puts "#{e.name} : #{e.code} (#{e.prob})" | |
} | |
end | |
def mean_code_length huf | |
sum = 0 | |
huf.each{ |e| | |
sum += e.code.size * e.prob | |
} | |
sum | |
end | |
def generate_run length, zero_prob, one_prob | |
q = [] | |
(0..length-1).each{ |e| | |
q << Node.new( e > 3 ? "0^#{e} 1" : "0" * e + "1", one_prob * zero_prob ** e) | |
} | |
q << Node.new("0^#{length}", zero_prob ** length) | |
q | |
end | |
def ran_mean_length length, zero_prob, one_prob | |
sum = 0 | |
(0..length-1).each{ |e| | |
sum += (e + 1) * one_prob * zero_prob ** e | |
} | |
sum += length * zero_prob ** length | |
end | |
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arr = [0.950, 0.030, 0.015, 0.005] | |
q = [] | |
arr.each_with_index{|e, i| | |
q << Node.new(i.to_s, e) | |
} | |
tree = make_bin_tree q | |
p tree[0].name | |
huf = huffmanize tree | |
print_huffman huf | |
p mean_code_length(huf) |
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a = 0.950 | |
b = 0.030 | |
c = 0.015 | |
d = 0.005 | |
q = [] | |
sum = 0 | |
5.times{ |i| | |
q << Node.new("A" * i + "B", a ** i * b) | |
sum += (i + 1) * a ** i * b | |
q << Node.new("A" * i + "C", a ** i * c) | |
sum += (i + 1) * a ** i * c | |
q << Node.new("A" * i + "D", a ** i * d) | |
sum += (i + 1) * a ** i * d | |
} | |
q << Node.new("AAAAA", a ** 5) | |
sum += a ** 5 * 5 | |
p q | |
tree = make_bin_tree q | |
p tree[0].name | |
huf = huffmanize tree | |
print_huffman huf | |
p mean_code_length(huf) | |
p sum | |
p mean_code_length(huf) / sum |
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q = generate_run 15, 0.9725, 0.0275 | |
tree = make_bin_tree q | |
p tree[0].name | |
huf = huffmanize tree | |
print_huffman huf | |
p mean_code_length(huf) | |
p mean_code_length(huf) / ran_mean_length(15, 0.9725, 0.0275) | |
p mean_code_length(huf) / ran_mean_length(15, 0.9725, 0.0275) * 2 |
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