Module: SleepingKingStudios::Tools::IntegerTools

Extended by:
IntegerTools
Included in:
IntegerTools
Defined in:
lib/sleeping_king_studios/tools/integer_tools.rb

Overview

Tools for working with integers and fixnums.

Constant Summary collapse

ROMANIZE_MIN =

Minimum integer value that can be converted to a roman numeral.

1
ROMANIZE_MAX =

Maximum integer value that can be converted to a roman numeral.

4999

Instance Method Summary collapse

Instance Method Details

#count_digits(integer, base: 10) ⇒ Integer

Returns the number of digits in the given integer when represented in the specified base. Ignores minus sign for negative numbers.

Examples:

With a positive number.

IntegerTools.count_digits(31)
#=> 2

With a negative number.

IntegerTools.count_digits(-141)
#=> 3

With a binary number.

IntegerTools.count_digits(189, :base => 2)
#=> 8

With a hexadecimal number.

IntegerTools.count_digits(16724838, :base => 16)
#=> 6


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# File 'lib/sleeping_king_studios/tools/integer_tools.rb', line 40

def count_digits integer, base: 10
  digits(integer.abs, :base => base).count
end

#digits(integer, base: 10) ⇒ Array<String>

Decomposes the given integer into its digits when represented in the given base.

Examples:

With a number in base 10.

IntegerTools.digits(15926)
#=> ['1', '5', '9', '2', '6']

With a binary number.

IntegerTools.digits(189, :base => 2)
#=> ['1', '0', '1', '1', '1', '1', '0', '1']

With a hexadecimal number.

IntegerTools.digits(16724838)
#=> ['f', 'f', '3', '3', '6', '6']


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# File 'lib/sleeping_king_studios/tools/integer_tools.rb', line 65

def digits integer, base: 10
  integer.to_s(base).split('')
end

#romanize(integer, additive: false) ⇒ String

Represents an integer between 1 and 4999 (inclusive) as a Roman numeral.

Examples:

IntegerTools.romanize(4) #=> 'IV'
IntegerTools.romanize(18) #=> 'XVIII'
IntegerTools.romanize(499) #=> 'CDXCIX'

Raises:

  • (RangeError) —

    If the integer is less than 1 or greater than 4999.



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# File 'lib/sleeping_king_studios/tools/integer_tools.rb', line 88

def romanize integer, additive: false
  # Validate input value.
  unless (ROMANIZE_MIN..ROMANIZE_MAX).include? integer
    raise RangeError.new "integer to romanize must be within range #{ROMANIZE_MIN} to #{ROMANIZE_MAX}"
  end # unless

  # Define conversion rules.
  rules = [
    '',
    '%one',
    '%one%one',
    '%one%one%one',
    additive ? '%one%one%one%one' : '%one%five',
    '%five',
    '%five%one',
    '%five%one%one',
    '%five%one%one%one',
    additive ? '%five%one%one%one%one' : '%one%ten',
    '%ten'
  ] # end array

  # Define numeral values.
  numerals = [
    %w(I V X),
    %w(X L C),
    %w(C D M),
    ['M', 'MMM', '']
  ] # end array numerals

  # Generate string representation.
  digits(integer).reverse.map.with_index do |digit, index|
    rules[digit.to_i]
      .gsub('%one',  numerals[index][0])
      .gsub('%five', numerals[index][1])
      .gsub('%ten',  numerals[index][2])
  end.reverse.join ''
end