New fractals folder (#4277)

* reupload

* delete file

* Move koch_snowflake.py to fractals-folder

* Move mandelbrot.py to fractals-folder

* Move sierpinski_triangle.py to fractals-folder

fractals/sierpinski_triangle.py

@@ -0,0 +1,76 @@
+#!/usr/bin/python
+
+"""Author Anurag Kumar | anuragkumarak95@gmail.com | git/anuragkumarak95
+
+Simple example of Fractal generation using recursive function.
+
+What is Sierpinski Triangle?
+>>The Sierpinski triangle (also with the original orthography Sierpinski), also called
+the Sierpinski gasket or the Sierpinski Sieve, is a fractal and attractive fixed set
+with the overall shape of an equilateral triangle, subdivided recursively into smaller
+equilateral triangles. Originally constructed as a curve, this is one of the basic
+examples of self-similar sets, i.e., it is a mathematically generated pattern that can
+be reproducible at any magnification or reduction. It is named after the Polish
+mathematician Wacław Sierpinski, but appeared as a decorative pattern many centuries
+prior to the work of Sierpinski.
+
+Requirements(pip):
+  - turtle
+
+Python:
+  - 2.6
+
+Usage:
+  - $python sierpinski_triangle.py <int:depth_for_fractal>
+
+Credits: This code was written by editing the code from
+http://www.riannetrujillo.com/blog/python-fractal/
+
+"""
+import sys
+import turtle
+
+PROGNAME = "Sierpinski Triangle"
+
+points = [[-175, -125], [0, 175], [175, -125]]  # size of triangle
+
+
+def getMid(p1, p2):
+    return ((p1[0] + p2[0]) / 2, (p1[1] + p2[1]) / 2)  # find midpoint
+
+
+def triangle(points, depth):
+
+    myPen.up()
+    myPen.goto(points[0][0], points[0][1])
+    myPen.down()
+    myPen.goto(points[1][0], points[1][1])
+    myPen.goto(points[2][0], points[2][1])
+    myPen.goto(points[0][0], points[0][1])
+
+    if depth > 0:
+        triangle(
+            [points[0], getMid(points[0], points[1]), getMid(points[0], points[2])],
+            depth - 1,
+        )
+        triangle(
+            [points[1], getMid(points[0], points[1]), getMid(points[1], points[2])],
+            depth - 1,
+        )
+        triangle(
+            [points[2], getMid(points[2], points[1]), getMid(points[0], points[2])],
+            depth - 1,
+        )
+
+
+if __name__ == "__main__":
+    if len(sys.argv) != 2:
+        raise ValueError(
+            "right format for using this script: "
+            "$python fractals.py <int:depth_for_fractal>"
+        )
+    myPen = turtle.Turtle()
+    myPen.ht()
+    myPen.speed(5)
+    myPen.pencolor("red")
+    triangle(points, int(sys.argv[1]))