Python cython：函数具有各种类型的参数

我正在尝试将一个旧的Python代码修改为Cython以提高速度。类有一个init函数，允许各种类型的参数：

class dRect:
    def __init__(self, *args):
        if len(args) == 1: # actual input is a list of four float numbers
            self.x0, self.y0, self.x1, self.y1 = args[0]
        elif len(args) == 4:  # actual input is four float numbers
            self.x0, self.y0, self.x1, self.y1 = args

# sample of initiating dRect instance
a = dRect([0, 1, 2, 3])
b = dRect(0, 1, 2, 3)

将其修改为Cython代码的正确方法是什么？或者我应该潜入这个世界的哪一部分？谢谢。

提速的大小（在任何情况下）取决于您可以做什么（在我的情况下，提速可达10倍）

。cdefed类将比非cdef类快（请参见下面测试中的MyCyClass vs MyPyClass）

在cdefed类的构造函数中，更喜欢传递Python浮点而不是传递Python整数。如果传入Python浮点而不是Python整数，则构造函数会更快。可能是因为将python float转换为double比将python integer转换为double更快

在自由cdef函数中使用_unew__;（）并避免元组初始化（如果可以避免的话）

测试：

这是我的时间安排

正在运行类型为（输入）=float的非cdef类的use构造函数

• 0.194803 0.199249 0.196051 0.2012200.265174μs（最慢）

运行类型为（输入）=浮点的use构造函数（cdef）

• 0.044000 0.048895 0.044641 0.045356 0.048148μs

运行类型为（输入）=int的使用构造函数（cdef）

• 0.090032 0.169924 0.089831 0.090147 0.091007μs

使用double init运行usenew（cdef），输入为double

• 0.026093 0.025533 0.029145 0.0236390.024517μs（最快）

使用双初始化运行usenew（cdef），输入为int

• 0.025040.024114 0.024084 0.025460 0.024183μs（最快，相当于上述速度）

运行usenew（cdef）和tuple init

• 0.042559 0.042985 0.042348 0.043527 0.043123μs

---

您试图实现什么目标？您可以将python代码按原样进行cythonize。这段代码没有太大的加速潜力。

cdef class MyCyClass:
    cdef public double x0
    cdef public double x1
    cdef public double x2
    cdef public double x3
    
    def __init__(self, *args):
        self.x0 = args[0]
        self.x1 = args[1]
        self.x2 = args[2]
        self.x3 = args[3]
    
class MyPyClass:
    def __init__(self, *args):
        self.x0 = args[0]
        self.x1 = args[1]
        self.x2 = args[2]
        self.x3 = args[3]

cdef new_MyCyClass_from_seq(args):
    my_obj = MyCyClass.__new__(MyCyClass)
    init_MyCyClass_from_seq(my_obj, args)

cdef init_MyCyClass_from_seq(MyCyClass my_obj, args):
    my_obj.x0 = args[0]
    my_obj.x1 = args[1]
    my_obj.x2 = args[2]
    my_obj.x3 = args[3]
    
cdef new_MyCyClass_from_double(double x0, double x1, double x2,  double x3):
    my_obj = MyCyClass.__new__(MyCyClass)
    init_MyCyClass_from_double(my_obj, x0, x1, x2, x3)
    
cdef init_MyCyClass_from_double(MyCyClass my_obj, double x0, double x1, double x2,  double x3):
    my_obj.x0 = x0
    my_obj.x1 = x1
    my_obj.x2 = x2
    my_obj.x3 = x3

def timefunc(name):
    def timedecorator(f):
        cdef Py_ssize_t L, i

        print("Running", name)
        for L in [1, 10, 100, 1000, 10000]:
            start = time.perf_counter() 
            f(L)
            end = time.perf_counter()
            print(format((end-start) / loops * 1e6, "2f"), end=" ")
            sys.stdout.flush()

        print("μs")
    return timedecorator

print()
print("INITIALISATIONS")
cdef Py_ssize_t loops = 100000

@timefunc("use constructor of non-cdef class with type(input) = float")
def _(Py_ssize_t L):
    cdef Py_ssize_t i
    
    my_obj = MyPyClass(1., 2., 3., 4.)
    
    for i in range(loops):
        my_obj = MyPyClass(1., 2., 3., 4.)
        
    return my_obj
    
    
@timefunc("use constructor (cdef) with type(input) = float")
def _(Py_ssize_t L):
    cdef MyCyClass my_obj = MyCyClass(1., 2., 3., 4.)
    cdef Py_ssize_t i
    
    for i in range(loops):
        # Notice the decimal place to denote 
        my_obj = MyCyClass(1., 2., 3., 4.)
        
    return my_obj
    
@timefunc("use constructor (cdef) with type(input) = int")
def _(Py_ssize_t L):
    cdef MyCyClass my_obj = MyCyClass(1, 2, 3, 4)
    cdef Py_ssize_t i
    
    for i in range(loops):
        my_obj = MyCyClass(1, 2, 3, 4)
        
    return my_obj
    
    
@timefunc("use new (cdef) with double init, input is double")
def _(Py_ssize_t L):
    cdef MyCyClass my_obj = MyCyClass(1, 2, 3, 4)
    cdef Py_ssize_t i
    
    for i in range(loops):
        my_obj = new_MyCyClass_from_double(1., 2., 3., 4.)
        
    return my_obj    
    
    
@timefunc("use new (cdef) with double init, input is int")
def _(Py_ssize_t L):
    cdef MyCyClass my_obj = MyCyClass(1, 2, 3, 4)
    cdef Py_ssize_t i
    
    for i in range(loops):
        new_MyCyClass_from_double(1, 2, 3, 4)
        
    return my_obj    
    
@timefunc("use new (cdef) and tuple init")
def _(Py_ssize_t L):
    cdef MyCyClass my_obj = MyCyClass(1., 2., 3., 4.)
    cdef Py_ssize_t i
    
    for i in range(loops):
        my_obj = new_MyCyClass_from_seq((1., 2., 3., 4.))
        
    return my_obj