DZone Snippets: sets code

Cantor's Sets with Processing

scvalex (Alexandru Scvortov) — Mon, 04 Feb 2008 11:08:31 GMT

This simple Processing programme generates the Cantor's Sets fractal.

Images are generated randomly, but tend to look like this.



int setHeight = 60;

color setColour = color(184 + random(-40, 40),

                        124 + random(-40, 40),

                        124 + random(-40, 40));

int wid = 600;



void setup() {

  size(wid, (int)((log(wid) / log(3) + 1) * (setHeight + 5)));

  background(0);

  smooth();

  

  cantorSet(10, 10, width - 20, setColour);

  

  save("cantorSet.png");

}



float rnd(float x) {

  return x + random(-20, 20);

}



void brushRect(int x, int y, int w, int h) {

  for (int i = 0; i < h; ++i) {

    float r = random(3);

    strokeWeight(r);

    float downpull = random(h / 4);

    float shudder = random(-2, 2);

    line(x + shudder, y + i, x + w - shudder, y + i + downpull);

  }

}



void cantorSet(int y, int offX, int wid, color col) {

  if ((y > height - 10) || (wid < 1))

    return;



  stroke(col);

  brushRect(offX, y, wid, setHeight);

  //fill(col);

  //rect(offX, y, wid, setHeight);

  

  color newCol = color(rnd(red(col)), rnd(green(col)),

                      rnd(blue(col)));

  cantorSet(y + setHeight + 5, offX, wid / 3, newCol);

  cantorSet(y + setHeight + 5, offX + wid*2/3, wid / 3, newCol);

}

Ruby Hash Power-Set

helder (Helder Ribeiro) — Thu, 13 Dec 2007 12:14:16 GMT

// adds a #power_set method to Hash class



# The Array power set is stolen from http://snippets.dzone.com/posts/show/3524

class Array

  # Returns the "power set" for this Array. This means that an array with all

  # subsets of the array's elements will be returned.

  def power_set

    # the power set line is stolen from http://johncarrino.net/blog/2006/08/11/powerset-in-ruby/

    inject([[]]){|c,y|r=[];c.each{|i|r<  end

end



class Hash

  def power_set

    # Returns the "power set" for this Hash. This means that a array with hashes of all

    # subsets of the hash's (key => value) pairs will be returned.

    # Example:

    # >> {:feedback_type=>"", :language_code=>"", :comment=>""}.power_set

    #

    # [{}, {:comment=>""}, {:language_code=>""}, {:language_code=>"", :comment=>""}, {:feedback_type=>""}, {:feedback_type=>"", :comment=>""}, {:feedback_type=>"", :language_code=>""}, {:feedback_type=>"", :language_code=>"", :comment=>""}]

    

    hash_to_array = self.to_a

    array_power_set = hash_to_array.power_set

    hash_power_set = array_power_set.collect { |pairs| pairs.inject({}) { |hash,pair| hash[pair[0]] = pair[1]; hash } }

    hash_power_set

  end

end