python print syntax error

I am experimenting with Hilbert curves written in Python in an Xcode IDE. The code listing is:

#  python code to run the hilbert curve pattern
#  from  http://www.fundza.com/algorithmic/space_filling/hilbert/basics/index.html
import sys, math

def hilbert(x0, y0, xi, xj, yi, yj, n):
    if n <= 0:
        X = x0 + (xi + yi)/2
        Y = y0 + (xj + yj)/2

        # Output the coordinates of the cv
        print '%s %s 0' % (X, Y)
    else:
        hilbert(x0,               y0,               yi/2, yj/2, xi/2, xj/2, n - 1)
        hilbert(x0 + xi/2,        y0 + xj/2,        xi/2, xj/2, yi/2, yj/2, n - 1)
        hilbert(x0 + xi/2 + yi/2, y0 + xj/2 + yj/2, xi/2, xj/2, yi/2, yj/2, n - 1)
        hilbert(x0 + xi/2 + yi,   y0 + xj/2 + yj,  -yi/2,-yj/2,-xi/2,-xj/2, n - 1)

def main():
    args = sys.stdin.readline()
    # Remain the loop until the renderer releases the helper...
    while args:
        arg = args.split()
        # Get the inputs
        pixels = float(arg[0])
        ctype = arg[1]
        reps = int(arg[2])
        width = float(arg[3])

        # Calculate the number of curve cv's
        cvs = int(math.pow(4, reps))

        # Begin the RenderMan curve statement
        print 'Basis \"b-spline\" 1 \"b-spline\" 1'
        print 'Curves \"%s\" [%s] \"nonperiodic\" \"P\" [' % (ctype, cvs)

        # Create the curve
        hilbert(0.0, 0.0, 1.0, 0.0, 0.0, 1.0, reps)

        # End the curve statement
        print '] \"constantwidth\" [%s]' % width

        # Tell the renderer we have finished
        sys.stdout.write('\377')
        sys.stdout.flush()

        # read the next set of inputs
        args = sys.stdin.readline()
if __name__ == "__main__":
    main()

I am getting the following error from Xcode: File "/Users/248239j/Desktop/hilbert/hilbertexe.py", line 12 print '%s %s' % (X, Y) ^ SyntaxError: invalid syntax

Would anyone have an alternative to that code line. Thanks in advance. I started using python today.

That's a problem with different Python-Versions.
Seems like this code was written for Python2.x but you're trying to run it with Python3.x.

The solution is to either use 2to3 to change these small differences automatically:

2to3 /Users/248239j/Desktop/hilbert/hilbertexe.py

Or manually replace the occurences of print <string> with print(<string>) (see Print is a function for more explanations).

Or just install Python2.x and run the code with that Python-Version

python2 /Users/248239j/Desktop/hilbert/hilbertexe.py