Convert real number to human readable number

human_readable_number.rb

class HumanReadableNumber
  attr_reader :b, :u_n

  def initialize(b:, u_n:)
    @b = b
    @u_n = u_n
  end

  def from(a)
    _E = [u_n.size-1, Math.log([1, a.abs].max, b).floor].min
    u = u_n[_E]
    f = (a.to_f / b**_E).round(2)
    f_d = (f - f.floor)
    f = f.to_i if f_d < 0.01
    "#{f}#{u}"
  end
end

jnumber = HumanReadableNumber.new(b: 10000, u_n: ["","万","億","兆"])
jnumber.from(2350) #=> "2350"
jnumber.from(1_2350) #=> "1.24万"
jnumber.from(123_0000_0000) #=> "123億"

byte = HumanReadableNumber.new(b: 1024, u_n: %w(B KB MB GB TB))
byte.from(1023) #=> "1023B"
byte.from(1024) #=> "1KB"
byte.from(160_300_000_000) #=> "149.29GB"

• $a$: real number $$a \in \mathbb{R}$$
• $F$: significand $$F \in \mathbb{R}$$
• $b$: base $$b \in \mathbb{N}^+$$
• $E$: exponent $$b \in \mathbb{N}$$
• ${u_n}$: unit numerical sequence
• $h$: human readable number $$F + u_n$$ (e.g. $$1.32 + \rm{MB}$$)

$$\begin{align} \{u_n\} &= \rm{B}, \rm{KB}, \rm{MB}, \rm{GB}, \rm{TB} \\\ \mathbb{H} &= \{ r + u \; | \; r \in \mathbb{R},\; u \in \{u_n\} \} \\\ a &= F b^E \\\ b &= 1024 \\\ E &= \min\{|\{u_n\}|-1,\; \lfloor \log_b \max\{1, |a|\} \rfloor\} \\\ F &= \frac{a}{b^E} \\\ F_r &= \frac{\lceil 10^2 F \rfloor}{10^2} \\\ h &= F_r + u_E,\; h \in \mathbb{H} \\\ \end{align}$$