class Statsample::Reliability::ItemCharacteristicCurve

Attributes

counts[R]

totals[R]

vector_total[R]

Public Class Methods

new(ds, vector_total=nil) click to toggle source

# File lib/statsample/reliability.rb, line 112
def initialize (ds, vector_total=nil)
  vector_total||=ds.vector_sum
  raise ArgumentError, "Total size != Dataset size" if vector_total.size!=ds.cases
  @vector_total=vector_total
  @ds=ds
  @totals={}
  @counts=@ds.fields.inject({}) {|a,v| a[v]={};a}
  process
end

Public Instance Methods

curve_field(field, item) click to toggle source

Return a hash with p for each different value on a vector

# File lib/statsample/reliability.rb, line 137
def curve_field(field, item)
  out={}
  item=item.to_s
  @totals.each do |value,n|
    count_value= @counts[field][value][item].nil? ? 0 : @counts[field][value][item]
    out[value]=count_value.quo(n)
  end
  out
end

process() click to toggle source

# File lib/statsample/reliability.rb, line 121
def process
  i=0
  @ds.each do |row|
    tot=@vector_total[i]
    @totals[tot]||=0
    @totals[tot]+=1
    @ds.fields.each  do |f|
      item=row[f].to_s
      @counts[f][tot]||={}
      @counts[f][tot][item]||=0
      @counts[f][tot][item] += 1
    end
    i+=1
  end
end