flatten recurse a little bit

recurse_test.py

from timeit import Timer
setup = """
from mathutils import Vector
from random import random
ul = [[[random(),random(),random()] for i in range(1000)]]

v1 = [[[random(),random(),random()] for i in range(1000)]]
v2 = [[[0,0,1]]]

def fullList(l, count):
    d = count - len(l)
    if d > 0:
        l.extend([l[-1] for a in range(d)])
    return

cross = lambda u,v:u.cross(v)[:]

def recurse_fxy( l1, l2, f, leve):
    if not leve:
        return f(Vector(l1), Vector(l2))
    else:
        max_obj = max(len(l1), len(l2))
        fullList(l1, max_obj)
        fullList(l2, max_obj)
        res = []
        res_append = res.append
        for i in range(len(l1)):
            res_append(recurse_fxy(l1[i], l2[i], f, leve - 1))
        return res

def recurse_fxy2(l1, l2, f, leve):
    if leve==1:
        max_obj = max(len(l1),len(l2)) 
        res = []
        res_append = res.append
        for i,obj in enumerate(zip(l1,l2)):
            res_append(f(Vector(obj[0]),Vector(obj[1])))
        if i < max_obj-1:
            if len(l1)-1==i:
                v_l1=Vector(l1[-1])
                for i in range(i,max_obj):
                    res_append(f(v_l1,Vector(l2[i])))
            else:
                v_l2=Vector(l2[-1])
                for i in range(i,max_obj):
                    res_append(f(Vector(l1[i]),v_l2))

        return res
    elif leve > 1:
        max_obj = max(len(l1),len(l2)) 
        fullList(l1, max_obj)
        fullList(l2, max_obj)    
        res = []
        for i in range(len(l1)):
            res.append(recurse_fxy2(l1[i], l2[i],f, leve-1))
        return res
"""

def test(r=3,times=1000):
    t1 = Timer("""w = recurse_fxy(ul,v1,cross,2)""", setup=setup)  
    print("fxy 1000:1000:", min(t1.repeat(r,times)))
    
    t2 = Timer("""w = recurse_fxy2(ul,v1,cross,2)""", setup=setup)  
    print("fxy2 1000:1000:", min(t2.repeat(r,times)))
    
    t3 = Timer("""w = recurse_fxy(ul,v2,cross,2)""", setup=setup)  
    print("fxy : 1000:1", min(t3.repeat(r,times)))
    
    t4 = Timer("""w = recurse_fxy2(ul,v2,cross,2)""", setup=setup)  
    print("fxy2: 1000:1", min(t4.repeat(r,times)))
    
test()

fxy 1000:1000: 1.0623891800059937
fxy2 1000:1000: 0.893612664018292
fxy : 1000:1 1.142882157000713
fxy2: 1000:1 0.6401150920137297