自动调整NumPy Recarray的大小

问题描述

我想创建一个numpy.recarray的子​​类，当将数据添加到当前长度之外的行时，该子类会自动调整大小.

I'd like to create a subclass of numpy.recarray that automatically resizes when data is added to a row outside of its current length.

下面的代码满足了我的大部分需求.

The code below does most of what I want.

class autorecarray(numpy.recarray):

   def __init__(self,*args,**kwargs):
      self._increment = 1
      numpy.recarray.__init__(self,args,kwargs)

   def __setitem__(self,ind,y):
      try:
         numpy.recarray.__setitem__(self,ind,y)
      except IndexError:
         self.resize((self.__len__()+self._increment,),refcheck=False)
         self.__setitem__(ind,y)

在此用例中效果很好:

a = utils.autorecarray((1,),formats=['i4','i4'])
a[1] = (1,2) # len(a) will now be 2

但是，这种用法将在numpy.core.records.recarray __getitem__方法上引发IndexError:

However, this usage will raise an IndexError on numpy.core.records.recarray __getitem__ method:

a[2]['f1'] = 3

我最初的尝试是也重写子类中的__getitem__方法，但是此代码不起作用.

My initial attempt was to also override the __getitem__ method in my subclass, but this code does not work.

def __getitem__(self,ind):
      try:
         numpy.recarray.__getitem__(self,ind)
      except IndexError:
         self.resize((self.__len__() + self._increment,),refcheck=False)
         self.__getitem__(ind)

它会自动扩展数组，但是现在数组中的每个项目都是None，无法更改.

It does automatically expand the array, but now every item in the array is None and cannot be changed.

有人可以告诉我我在做什么错吗?

Can anyone tell me what I'm doing wrong?

推荐答案

首先，您在numpy.recarray.__init__调用中缺少星号:

First of all you're missing the asterisks in the numpy.recarray.__init__ call:

def __init__(self, *args, **kwargs):
    self._increment = 1
    numpy.recarray.__init__(self, *args, **kwargs)

第二，您在__getitem__中缺少return语句:

And second, you're missing return statements in the __getitem__:

def __getitem__(self,ind):
    try:
        return numpy.recarray.__getitem__(self,ind)
    except IndexError:
        self.resize((self.__len__() + self._increment,),refcheck=False)
        return self.__getitem__(ind)

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