In [2]:
c=circle((1,0),5) # arguments are center, radius
# Returns a Graphics object
In [3]:
plot(c) # Graphics objects can be plotted
Out[3]:
In [4]:
c2 = circle((-1,-1), 3)
In [5]:
plot(c+c2) # You can add Graphics objects together and plot them
Out[5]:
In [6]:
tri = polygon([(0,0), (1,1), (2,1)]) # returns a filled in polygon
In [7]:
plot(tri)
Out[7]:
In [9]:
quad = polygon([(0,0), (1,1), (2,1), (3,0)]) # a quadrilateral
In [10]:
plot(quad)
Out[10]:
In [12]:
# Now we will try to draw a Sierpinski triangle
In [13]:
# code for 0th iteration
equi_tri = polygon([(0,0), (1,0), (1/2, sqrt(3)/2)])
In [14]:
plot(equi_tri)
Out[14]:
In [15]:
# Code for a single equilateral triangle
def tri(basept, size):
    """Return an equilateral triangle with left vertex at 
    basept (x,y)
    and given size."""
    (x,y) = basept
    return polygon([(0+x,0+y), (size*1+x,0+y), \
                    (size*(1/2)+x, size*sqrt(3)/2 +y)])
In [16]:
tri((1,0), 0.7)
Out[16]:
In [17]:
# code for 1st iteration
t1 = tri((0,0), 1/2)
t2 = tri((1/2,0), 1/2)
t3 = tri((1/4,sqrt(3)/4), 1/2)
plot(t1+t2+t3)
Out[17]:
In [20]:
# code for nth iteration
def sierp_tri(basept, size, iter):
    """Draw sierpinski triangle of given size, number of 
    iterations, with left vertex at basept. Use recursion."""
    # graphic = Graphics() # makes an empty graphics object
    # will add triangles to this to get final sierp tri
    
    if iter == 0:
        return tri(basept, size)
    else:
        # copy the code for 1st iteration, but replace
        # each triangle with a sierp_tri with iter-1 iterations
        (x,y) = basept
        t1 = sierp_tri(basept, size/2, iter-1)
        t2 = sierp_tri((x+size/2,y), size/2, iter-1)
        t3 = sierp_tri((x+size*1/4, y+size*sqrt(3)/4), size/2, iter-1)
        return t1 + t2 + t3
In [21]:
sierp_tri((0,0), 1, 5)
Out[21]:
In [43]:
sierp_tri((0,0), 1, 6).save("sierp_tri_6.pdf") 
# saves graphics object as a pdf file