numpy子类将不接受来自python继承类的__new__参数

Question

I've created a subclass of ndarray called "Parray" which takes two arguments: p, and dimensionality. It works fine on its own. Now, I want to create a class called SirPlotsAlot, which inherits Parray without all the fancy new and array_finalize etc.

import numpy as np

class Parray(np.ndarray):
    def __new__(self, p = Parameters(), dimensionality = 2):

        print "Initializing Parray with initial dimensionality %s..." % dimensionality

        self.p = p # store the parameters

        if dimensionality == 2:
            shape = (p.nx, p.ny)
            self.pshape = shape
        elif dimensionality == 3:
            shape=(p.nx, p.ny, p.nx)
            self.pshape = shape
        else:
            raise NotImplementedError, "dimensionality must be 2 or 3"

        # ...Set other variables (ellided)

        subarr = np.ndarray.__new__(self, shape, dtype, buffer, offset, strides, order)
        subarr[::] = np.zeros(self.pshape) # initialize to zero
        return subarr
...

class SirPlotsAlot(Parray):
    def __init__(self, p = Parameters(), dimensions = 3):
        super(SirPlotsAlot, self).__new__(p, dimensions)     # (1)

Objects in my program share sets of parameters by passing an object p = Parameters() back and forth.

Now, when I type (the file is auxiliary.py):

import auxiliary
from parameters import Parameters
p = Parameters()
s = auxiliary.SirPlotsAlot(p, 3)

expecting to get a nice "Initializing Parray with initial dimensionality 3", I get "2", instead. BUT if I type:

import auxiliary
s = auxiliary.SirPlotsAlot()

I get

---> 67             shape = (p.nx, p.ny)
"AttributeError: 'int' object has no attribute 'nx'"

It thinks "p" is an int, which it is not. I can get lots of weird seemingly unrelated errors if I play around with it. The int it thinks it is is "2". I'm completely lost.

I've tried with and without the # (1) comment (the super call).

Other errors from playing around include "AttributeError: 'list' object has no attribute 'p'", "TypeError: new () takes exactly 2 arguments (1 given)", "ValueError: need more than 0 values to unpack" (I replaced new 's arguments with *args, something I don't understand very well).

Answer 1

I'm going to echo kindall, and say "don't use __new__ ". Your Parray.__new__ method looks more like an initialisation, and should be using __init__ , like it's subclass is.