# File lib/tour/facets/array/percentile.rb, line 12 def percentile(p) sorted_array = self.sort rank = (p.to_f / 100) * (self.length + 1) if self.length == 0 return nil elsif rank.to_i == rank #fractional_part? sample_0 = sorted_array[rank.truncate - 1] sample_1 = sorted_array[rank.truncate] fractional_part = rank.abs.modulo(1) return (fractional_part * (sample_1 - sample_0)) + sample_0 else return sorted_array[rank.to_i - 1] end end