DZone Snippets: Andyv's Code Snippets

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AndyV (Andy Vanasse) — Thu, 07 Jun 2007 18:18:00 GMT

// description of your code here



















	Tracy

	

		Position: President

	



	Andy

	

		Position: Architect

	



	Ron

	

		Position: Operations Manager

Metaphone calculation

AndyV (Andy Vanasse) — Thu, 07 Jun 2007 17:07:38 GMT

// Calculate's Lawrence Phillip's basic metaphone (a more advanced code for matching names)



class Metaphone

  TRANSFORMATIONS = [[/\A[gkp]n/  ,  'n'],   # gn, kn, or pn at the start turns into 'n'

                     [/\Ax/       ,  's'],   # x at the start turns into 's'

                     [/\Awh/      ,  'w'],   # wh at the start turns into 'w'

                     [/mb\z/      ,  'm'],   # mb at the end turns into 'm'

                     [/sch/       ,  'sk'],  # sch sounds like 'sk'

                     [/x/         ,  'ks'],

                     [/cia/       ,  'xia'], # the 'c' -cia- and -ch- sounds like 'x'

                     [/ch/        ,  'xh'],

                     [/c([iey])/  ,  's\1'], # the 'c' -ce-, -ci-, or -cy- sounds like 's'

                     [/ck/        ,  'k'],

                     [/c/         ,  'k'],

                     [/dg([eiy])/ ,  'j\1'], # the 'dg' in -dge-, -dgi-, or -dgy- sounds like 'j'

                     [/d/         ,  't'],

                     [/gh/        ,  ''],

                     [/gned/      ,  'ned'],

                     [/gn((?![aeiou])|(\z))/ ,  'n'],

                     [/g[eiy]/    ,  'j'],

                     [/ph/        ,  'f'],

                     [/[aeiou]h(?![aeoiu])/ ,  '\1'], # 'h' is silent after a vowel unless it's between vowels

                     [/q/         ,  'k'],

                     [/s(h|(ia)|(io))/ ,  'x\1'],

                     [/t((ia)|(io))/,  'x\1'],

                     [/th/        ,  '0'],

                     [/v/         ,  'f'],

                     [/w(?![aeiou])/ ,  ''],

                     [/y(?![aeiou])/ ,  ''],

                     [/z/         ,  's']

                    ]

                    

  def self.create_metaphone(aWord)

    word = aWord.to_s.downcase

    TRANSFORMATIONS.each{|transform| word.gsub!(transform.first, transform.last)}

    'a'.upto('z'){|letter| word.gsub!(letter*2, letter)}

    return (word[0].chr + word[1..word.length-1].gsub(/[aeiou]/, '')).upcase

  end

end

Soundex calculation

AndyV (Andy Vanasse) — Wed, 25 Apr 2007 16:44:43 GMT

// Calculates a soundex for a name in (basic) conformance to the
// algorithm discussed at http://en.wikipedia.org/wiki/Soundex
// It's wrapped in a class primarily to contain the ALPHA_MAP.



class Soundex

  ALPHA_MAP = { 'a' => nil, 'b' => '1', 'c' => '2', 'd' => '3', 'e' => nil, 'f' => '1',

                'g' => '2', 'h' => nil, 'i' => nil, 'j' => '2', 'k' => '2', 'l' => '4',

                'm' => '5', 'n' => '5', 'o' => nil, 'p' => '1', 'q' => '2', 'r' => '6',

                's' => '2', 't' => '3', 'u' => nil, 'v' => '1', 'w' => nil, 'x' => '2',

                'y' => nil, 'z' => 2

              }

              

  def self.calculate(aName)

    ary = []

    # map all the letters in the supplied name

    aName.downcase.each_byte{|ltr| ary.push(ALPHA_MAP[ltr.chr])}

    # now drop out repeated values

    ary.length.downto(1){ |idx| ary[idx] = nil if ary[idx]==ary[idx-1] }

    # remove the nil elements

    ary.compact!

    # pad with zeroes

    0.upto(2){ ary.push('0')}

    # Replace the first value with the first letter of the supplied name

    ary[0] = aName[0].chr

    # return the first four elements of the array as a string

    return ary[0..3].to_s

  end

end

Toggling associations for Many-to-Many relationships

AndyV (Andy Vanasse) — Fri, 13 Oct 2006 21:24:26 GMT

I have a rather greedy object that needs to be associated with most of the other objects in my domain. To compensate, I've written the following code to take care of toggling the association (adding a record in the join table if it does not exist or removing it if it does). I've called it toggle because it's physically represented by toggling the state of a checkbox on a form.



def toggle_child_assoc(child_object)

    # check to see if the parent recognizes the collection_name

    collection_name = child_object.class.to_s.downcase.pluralize

    aCollection = self.send(collection_name) if self.respond_to?(collection_name)

    unless aCollection

      return false

    end



    # If the parent recognizes the collection_name then check to see if the child_object

    # appears in the collection.  If so then remove it, otherwise add it.

    if aCollection.include?(child_object)

      self.send("remove_%s" % collection_name, child_object)

    else

      self.send("add_%s" % collection_name, child_object)

    end

    true

end

First the code determines if the "parent" of the association actually supports a collection of the child object's class by testing to see if it responds to the method corresponding to the name of the collection. If not the method returns false. Otherwise, the method checks to see if the parent object already has the child in its collection. If it does it builds a call to remove_collection_name to remove it and if it does not it builds a call to add_collection_name to add it.

The code could be improved by adding a means by which to override the collection_name. This override would be used in the event that the child is a subclass of a class with which the parent has a habtm relationship.