Class: Stella::Stats

Inherits:
Object
  • Object
show all
Defined in:
lib/stella/stats.rb

Overview

Based on Mongrel::Stats, Copyright © 2005 Zed A. Shaw

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name) ⇒ Stats

Returns a new instance of Stats.



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# File 'lib/stella/stats.rb', line 8

def initialize(name)
  @name = name
  reset
end

Instance Attribute Details

#max ⇒ Object (readonly)

Returns the value of attribute max.



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# File 'lib/stella/stats.rb', line 6

def max
  @max
end

#min ⇒ Object (readonly)

Returns the value of attribute min.



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# File 'lib/stella/stats.rb', line 6

def min
  @min
end

#n ⇒ Object (readonly)

Returns the value of attribute n.



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# File 'lib/stella/stats.rb', line 6

def n
  @n
end

#sum ⇒ Object (readonly)

Returns the value of attribute sum.



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# File 'lib/stella/stats.rb', line 6

def sum
  @sum
end

#sumsq ⇒ Object (readonly)

Returns the value of attribute sumsq.



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# File 'lib/stella/stats.rb', line 6

def sumsq
  @sumsq
end

Instance Method Details

#+(obj) ⇒ Object 



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# File 'lib/stella/stats.rb', line 13

def +(obj)
  puts obj.class
end

#dump(msg = "", out = STDERR) ⇒ Object

Dump this Stats object with an optional additional message.



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# File 'lib/stella/stats.rb', line 38

def dump(msg = "", out=STDERR)
  out.puts "#{msg}: #{self.inspect}"
end

#inspect ⇒ Object

Returns a common display (used by dump)



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# File 'lib/stella/stats.rb', line 43

def inspect
  v = [mean, @n, @sum, @sumsq, sd, @min, @max]
  t = %w"N=%0.4f SUM=%0.4f SUMSQ=%0.4f SD=%0.4f MIN=%0.4f MAX=%0.4f"
  "%0.4f: " << t % v
end

#mean ⇒ Object

Calculates and returns the mean for the data passed so far.



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# File 'lib/stella/stats.rb', line 62

def mean
  @sum / @n
end

#reset ⇒ Object

Resets the internal counters so you can start sampling again.



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# File 'lib/stella/stats.rb', line 18

def reset
  @n, @sum, @sumsq = 0.0, 0.0, 0.0
  @last_time = Time.new
  @min, @max = 0.0, 0.0
end

#sample(s) ⇒ Object

Adds a sampling to the calculations.



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# File 'lib/stella/stats.rb', line 25

def sample(s)
  @sum += s
  @sumsq += s * s
  if @n == 0
    @min = @max = s
  else
    @min = s if @min > s
    @max = s if @max < s
  end
  @n+=1
end

#sd ⇒ Object

Calculates the standard deviation of the data so far.



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# File 'lib/stella/stats.rb', line 67

def sd
  return 0.0 if @n <= 1
  # (sqrt( ((s).sumsq - ( (s).sum * (s).sum / (s).n)) / ((s).n-1) ))
  begin
    return Math.sqrt( (@sumsq - ( @sum * @sum / @n)) / (@n-1) )
  rescue Errno::EDOM
    return 0.0
  end
end

#tick ⇒ Object

Adds a time delta between now and the last time you called this. This will give you the average time between two activities.

An example is:

t = Stats.new("do_stuff")
10000.times { do_stuff(); t.tick }
t.dump("time")



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# File 'lib/stella/stats.rb', line 87

def tick
  now = Time.now
  sample(now - @last_time)
  @last_time = now
end

#to_f ⇒ Object 



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# File 'lib/stella/stats.rb', line 53

def to_f
  mean.to_f
end

#to_i ⇒ Object 



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# File 'lib/stella/stats.rb', line 57

def to_i
  mean.to_i
end

#to_s ⇒ Object 



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# File 'lib/stella/stats.rb', line 49

def to_s
  mean.to_s
end