class FlatKit::StatType::NumericalStats
Stats
object will keep track of the min, max, count, sum and sumsq and when you want you may also retrieve the mean, stddev and rate.
this contrived example shows getting a list of all the files in a directory and running stats on file sizes.
s = FlatKit::Stats.new dir = ARGV.shift || Dir.pwd Dir.entries( dir ).each do |entry| fs = File.stat( entry ) if fs.file? then s.update( fs.size ) end end %w[ count min max mean sum stddev rate ].each do |m| puts "#{m.rjust(6)} : #{s.send( m ) }" end
Attributes
A list of the available stats
Public Class Methods
# File lib/flat_kit/stat_type/numerical_stats.rb, line 45 def self.all_stats @all_stats ||= %w[ count max mean min mode rate stddev sum sumsq unique_count unique_values ] end
# File lib/flat_kit/stat_type/numerical_stats.rb, line 41 def self.default_stats @default_stats ||= %w[ count max mean min rate stddev sum sumsq ] end
FlatKit::StatType::NominalStats::new
# File lib/flat_kit/stat_type/numerical_stats.rb, line 49 def initialize(collecting_frequencies: false) super @min = Float::INFINITY @max = -Float::INFINITY @sum = 0.0 @sumsq = 0.0 end
Public Instance Methods
Return the arithmetic mean of the values put into the Stats
object. If no values have passed through the stats object then 0.0 is returned;
# File lib/flat_kit/stat_type/numerical_stats.rb, line 83 def mean return 0.0 if @count.zero? return @sum / @count end
Return the count
divided by sum
.
In many cases when Stats#update( value ) is called, the value is a unit of time, typically seconds or microseconds. rate
is a convenience for those times. In this case, where value is a unit if time, then count divided by sum is a useful value, i.e. +something per unit of time+.
In the case where value is a non-time related value, then the value returned by rate is not really useful.
# File lib/flat_kit/stat_type/numerical_stats.rb, line 101 def rate return 0.0 if @sum.zero? return @count / @sum end
Return the standard deviation of all the values that have passed through the Stats
object. The standard deviation has no meaning unless the count is > 1, therefore if the current stat.count is < 1 then 0.0 will be returned;
# File lib/flat_kit/stat_type/numerical_stats.rb, line 114 def stddev return 0.0 unless @count > 1 Math.sqrt((@sumsq - ((@sum * @sum)/@count)) / (@count - 1)) end
Update the running stats with the new value. Return the input value.
# File lib/flat_kit/stat_type/numerical_stats.rb, line 62 def update(value) @mutex.synchronize do @min = (value < @min) ? value : @min @max = (value > @max) ? value : @max @count += 1 @sum += value @sumsq += (value * value) # from Nomnial update @frequencies[value] += 1 if @collecting_frequencies end return value end