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class SparseVector < Hash
def initialize arg=nil
super
self.default = 0
if arg.is_a? Array
from_a arg
end
end
def from_a a
a.each_with_index { |i,j| self[j] = i }
end
def from_h h
h.each_pair { |k,v| self[k] = v }
end
def from_s s
from_h eval(s)
end
def sum
self.values.inject(:+)
end
def approx_eql? other, p=10**-10
return false if !other
return false if other.size!=self.size
return false if other.keys.sort!=self.keys.sort
self.keys.each { |k|
return false if (self[k]-other[k]).abs>p
}
return true
end
def average
self.sum/self.size.to_f
end
def variance
avg = self.average
var = 0.0
self.values.each { |i| var += (avg - i)**2 }
return var
end
def stddev
Math.sqrt self.variance
end
def dot other
sum = 0.0
self.each_pair { |k,v| sum += v * other[k] }
return sum
end
def zeros n
(0).upto(n-1) { |i| self[i] = 0.0 }
end
def magnitude
Math.sqrt self.values.inject { |sum,i| sum+i**2 }
end
def cosinus_sim other
self.dot(other)/(self.magnitude*other.magnitude)
end
def euclidian_dist other
dims = [self.keys, other.keys].flatten.uniq
sum = 0.0
dims.each { |d| sum += (self[d] - other[d])**2 }
return Math.sqrt(sum)
end
# FIXME
def from_kv_file fn, sep=' '
f = ReadFile.new(fn)
while line = f.gets
key, value = line.strip.split sep
value = value.to_f
self[key] = value
end
end
# FIXME
def to_kv sep='='
a = []
self.each_pair { |k,v|
a << "#{k}#{sep}#{v}"
}
return a.join ' '
end
def join_keys other
self.keys + other.keys
end
def + other
new = SparseVector.new
join_keys(other).each { |k|
new[k] = self[k]+other[k]
}
return new
end
def - other
new = SparseVector.new
join_keys(other).each { |k|
new[k] = self[k]-other[k]
}
return new
end
def * scalar
raise ArgumentError, "Arg is not numeric #{scalar}" unless scalar.is_a? Numeric
new = SparseVector.new
self.keys.each { |k|
new[k] = self[k] * scalar
}
return new
end
end
def mean_sparse_vector array_of_vectors
mean = SparseVector.new
array_of_vectors.each { |i|
i.each_pair { |k,v|
mean[k] += v
}
}
n = array_of_vectors.size.to_f
mean.each_pair { |k,v| mean[k] = v/n }
return mean
end
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