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require 'more_math'
module MoreMath
# A histogram gives an overview of a sequence's elements.
class Histogram
# Create a Histogram for the elements of +sequence+ with +bins+ bins.
def initialize(sequence, bins = 10)
@sequence = sequence
@bins = bins
@result = compute
end
# Number of bins for this Histogram.
attr_reader :bins
# Return the computed histogram as an array of arrays.
def to_a
@result
end
# Display this histogram to +output+, +width+ is the parameter for
# +prepare_display+
def display(output = $stdout, width = 50)
d = prepare_display(width)
for l, bar, r in d
output << "%11.5f -|%s\n" % [ (l + r) / 2.0, "*" * bar ]
end
self
end
private
# Returns an array of tuples (l, c, r) where +l+ is the left bin edge, +c+
# the +width+-normalized frequence count value, and +r+ the right bin
# edge. +width+ is usually an integer number representing the width of a
# histogram bar.
def prepare_display(width)
r = @result.reverse
factor = width.to_f / (r.transpose[1].max)
r.map { |l, c, r| [ l, (c * factor).round, r ] }
end
# Computes the histogram and returns it as an array of tuples (l, c, r).
def compute
@sequence.empty? and return []
last_r = -Infinity
min = @sequence.min
max = @sequence.max
step = (max - min) / bins.to_f
Array.new(bins) do |i|
l = min + i * step
r = min + (i + 1) * step
c = 0
@sequence.each do |x|
x > last_r and (x <= r || i == bins - 1) and c += 1
end
last_r = r
[ l, c, r ]
end
end
end
end
Version data entries
9 entries across 9 versions & 1 rubygems