Feature #4787: Integer#each_modulo(n)

• Status: Closed
• Assignee: matz (Yukihiro Matsumoto)
• Target version: -

[mrkn (Kenta Murata)]

I suggest a new feature of Integer to enumerate by iterated Integer#modulo.
An example implementation in Ruby is the following code:

class Integer
  def each_modulo(n)
    raise ArgumentError, "argument must be an Integer" unless n.is_a? Integer
    raise ArgumentError, "argument must be larger than 1" if n <= 1
    return Enumerator.new(self, :each_modulo, n) unless block_given?
    q = self
    while q > 0
      q, r = q.divmod(n)
      yield(r)
    end
  end
end

p 133.each_modulo(3).to_a #=> [1, 2, 2, 1, 1]

The following code is an example use of the feature:

class Integer
  def each_thousand_separation
    each_modulo(1000)
  end

  def thousand_separated_string(sep=',')
    each_thousand_separation.map(&'%03d'.method(:%)).inject{|s, n| n + sep + s }
  end
end

p 100_000_000_200.thousand_separated_string #=> "100,000,000,200"

I make an implementation in C, and attach the patch for that.

[mrkn (Kenta Murata)]

• ruby -v changed from ruby 1.9.3dev (2011-05-27 trunk 31745) [x86_64-darwin10.7.0] to -

Hi,

I believe I've sent the following feature request to ruby-core,
but I sent to ruby-dev by mistake.

--
Kenta Murata
Sent with Sparrow (http://www.sparrowmailapp.com)

Forwarded Message：

From: Kenta Murata [e-mail]
In Reply To: [e-mail]
To: ruby developers list [e-mail]
Date: 2011-05-27 13:21:06
Subject: [ruby-dev:43586] [Ruby 1.9 - Bug #4787][Open] Integer#each_modulo(n)

Issue #4787 has been reported by Kenta Murata.

---

Bug #4787: Integer#each_modulo(n)
http://redmine.ruby-lang.org/issues/4787

Author: Kenta Murata
Status: Open
Priority: Normal
Assignee: Yukihiro Matsumoto
Category: core
Target version: 1.9.3
ruby -v: ruby 1.9.3dev (2011-05-27 trunk 31745) [x86_64-darwin10.7.0]

I suggest a new feature of Integer to enumerate by iterated Integer#modulo.
An example implementation in Ruby is the following code:

class Integer
def each_modulo(n)
raise ArgumentError, "argument must be an Integer" unless n.is_a? Integer
raise ArgumentError, "argument must be larger than 1" if n <= 1
return Enumerator.new(self, :each_modulo, n) unless block_given?
q = self
while q > 0
q, r = q.divmod(n)
yield(r)
end
end
end

p 133.each_modulo(3).to_a #=> [1, 2, 2, 1, 1]

The following code is an example use of the feature:

class Integer
def each_thousand_separation
each_modulo(1000)
end

def thousand_separated_string(sep=',')
each_thousand_separation.map(&'%03d'.method(:%)).inject{|s, n| n + sep + s }
end
end

p 100_000_000_200.thousand_separated_string #=> "100,000,000,200"

I make an implementation in C, and attach the patch for that.

--
http://redmine.ruby-lang.org

[nobu (Nobuyoshi Nakada)]

• Tracker changed from Bug to Feature

[matz (Yukihiro Matsumoto)]

• Target version changed from 1.9.3 to 2.0.0

[trans (Thomas Sawyer)]

Why not just let #modulo/#divmod take a block, rather than define a new method?

[shyouhei (Shyouhei Urabe)]

• Status changed from Open to Assigned

[yhara (Yutaka HARA)]

• Target version changed from 2.0.0 to 2.6

[mrkn (Kenta Murata)]

• Related to Feature #12116: `Fixnum#divmod`, `Bignum#divmod` with multiple arguments added

[mrkn (Kenta Murata)]

• Related to Feature #12447: Integer#digits for extracting digits of place-value notation in any base added

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)

[duerst (Martin Dürst)]

This only gives the 'mod' part. Why not extend this to get both the 'div' part and the 'mod' part back (see also comment #4)?

And why not allow an array of integers as an argument? Some conventions for displaying large numbers with separators are not uniform, in particular in India (see https://en.wikipedia.org/wiki/Indian_numbering_system).

[mrkn (Kenta Murata)]

• Status changed from Assigned to Closed

This was resolved by #12447.