Base N to Base M conversions (using Numeric arrays, not an extended alphabet)

base.py

"""
Port the to_base/from_base functions from Ruby to Python
"""
from __future__ import division

def __to_base_notation(value, base):
  result = []
  while value > 0 or not len(result):
    part = value % base
    value = (value - part) / base
    result.append(part)
  result.reverse()
  return result

__to_base_notation(152, 10)

def __from_base_notation(parts, base):
  value = 0
  for exponent, digit in enumerate(reversed(parts)):
    value += digit * (base ** exponent)
  return value

__from_base_notation([1,5,2], 10)

base.rb

# Convert from any base to any base using arrays of Numerics (not an extended alphabet)
# Only positive values considered.
#
# [1,5,2].from_base 10 => 152
# 152.to_base 10 => [1,5,2]
#
# Don't forget that Ruby handles bases 1..36 nativly (with an extended alphabet) with to_s and to_i:
# 0b01010100.to_s 16          #=> "54"
# 0xc8.to_s 2                 #=> "11001000"
# "10111001".to_i(2).to_s(16) #=> "b9"
#
# For a gem like this, but allows setting custom extended alphabets:
# https://github.com/rubyworks/radix

class Array
  def from_base base
    self.reverse.each.with_index.inject 0 do |value,(digit,exponent)|
      value + digit * (base ** exponent)
    end
  end
end

class Numeric
  def to_base base
    value = self.abs
    result = []
    begin
      part = value % base
      value = (value - part) / base
      result << part
    end while value > 0
    result.reverse
  end
end