Class: Statsample::Histogram

Inherits:
Object
  • Object
show all
Includes:
GetText
Defined in:
lib/statsample/histogram.rb

Overview

A histogram consists of a set of bins which count the number of events falling into a given range of a continuous variable x.

This implementations follows convention of GSL for specification.

* Verbatim: *

The range for bin[i] is given by range[i] to range[i+1]. 
For n bins there are n+1 entries in the array range. 
Each bin is inclusive at the lower end and exclusive at the upper end. 
Mathematically this means that the bins are defined 
by the following inequality,

 bin[i] corresponds to range[i] <= x < range[i+1]

Here is a diagram of the correspondence between ranges and bins
on the number-line for x,

    [ bin[0] )[ bin[1] )[ bin[2] )[ bin[3] )[ bin[4] )
 ---|---------|---------|---------|---------|---------|---  x
  r[0]      r[1]      r[2]      r[3]      r[4]      r[5]

In this picture the values of the range array are denoted by r. 
On the left-hand side of each bin the square bracket ‘[’ denotes 
an inclusive lower bound ( r <= x), and the round parentheses ‘)’ 
on the right-hand side denote an exclusive upper bound (x < r). 
Thus any samples which fall on the upper end of the histogram are 
excluded. 
If you want to include this value for the last bin you will need to 
add an extra bin to your histogram.

Reference: www.gnu.org/software/gsl/manual/html_node/The-histogram-struct.html

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(p1, min_max = false, opts = Hash.new) ⇒ Histogram

Returns a new instance of Histogram.



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# File 'lib/statsample/histogram.rb', line 52

def initialize(p1, min_max=false, opts=Hash.new)
  
  if p1.is_a? Array
    range=p1
    n_bins=p1.size-1
  elsif p1.is_a? Integer
    n_bins=p1
  end
  
  @bin=[0.0]*(n_bins)
  if(min_max)
    min, max=min_max[0], min_max[1]
    range=Array.new(n_bins+1)
    (n_bins+1).times {|i| range[i]=min+(i*(max-min).quo(n_bins)) }
  end
  range||=[0.0]*(n_bins+1)
  set_ranges(range)
  @name=""
  opts.each{|k,v|
  self.send("#{k}=",v) if self.respond_to? k
  }
end

Instance Attribute Details

#bin ⇒ Object (readonly)

Returns the value of attribute bin.



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# File 'lib/statsample/histogram.rb', line 48

def bin
  @bin
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/statsample/histogram.rb', line 47

def name
  @name
end

#range ⇒ Object (readonly)

Returns the value of attribute range.



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# File 'lib/statsample/histogram.rb', line 49

def range
  @range
end

Class Method Details

.alloc(n_bins, range = nil, opts = Hash.new) ⇒ Object 



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# File 'lib/statsample/histogram.rb', line 42

def alloc(n_bins, range=nil, opts=Hash.new)
  Histogram.new(n_bins, range)
  
end

Instance Method Details

#increment(x, w = 1) ⇒ Object 



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# File 'lib/statsample/histogram.rb', line 75

def increment(x, w=1)
  if x.is_a? Array
    x.each{|y| increment(y,w) }
  elsif x.is_a? Numeric
    (range.size-1).times do |i|
      if x>=range[i] and x<range[i+1]
        @bin[i]+=w
        break
      end
    end
  end
end

#report_building_text(generator) ⇒ Object 



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# File 'lib/statsample/histogram.rb', line 91

def report_building_text(generator)
  anchor=generator.toc_entry(_("Histogram %s") % [@name])
  range.each_with_index do |r,i|
    next if i==@bin.size
    generator.text(sprintf("%4.2f : %d", r, @bin[i]))
  end
end

#set_ranges(range) ⇒ Object 



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# File 'lib/statsample/histogram.rb', line 87

def set_ranges(range)
  raise "Range size should be bin+1" if range.size!=@bin.size+1
  @range=range
end