奇怪的python对象属性错误

Question

我遇到了一个非常奇怪的问题。

请参阅以下代码。在课堂上有一个奇怪的属性＆＃39;与所有其他属性一样定义。 （由

标记的代码的问题区域

========================

========================）

但是当我训练在其中一个函数中访问它时，它会引发一个错误，说该属性不存在。

但是，如果删除在函数中访问该属性的行，然后创建一个对象，则可以访问该对象的属性...

请你看看代码，看看出了什么问题，我在这里结束了......：＆＃39;（

class img_iter(DataIter):
    def __init__(self, dir_train, 
             dir_label, 
             data_name = "data", 
             label_name = "softmax_label", 
             last_batch_handle = 'pad',
             batch_size = 1,
             #===================================================
             #===================================================
             color_mean = (117, 117, 117),
             #===================================================
             #===================================================
             cut_off_size = None):
        super().__init__()
        # directories as attributes
        self.dir_train = dir_train
        self.dir_label = dir_label
        # names
        self.data_name = data_name
        self.label_name = label_name
        # read data and label files into list
        self.img_data_lst = [s for s in os.listdir(dir_train) if '.jpg' in s]
        self.img_data_iter = iter(self.img_data_lst)
        if self.dir_label is not None:
            self.img_label_lst = [s for s in os.listdir(dir_label) if '.gif' in s]
        # number of data files
        self.num_data = len(self.img_data_lst)
        # read data when initialising
        self.data, self.label = self._read()
        # size limiter
        self.cut_off_size = cut_off_size
        # batch size
        self.batch_size = batch_size
        # data cursor
        self.cursor = -batch_size
        #===================================================
        #===================================================
        self.weird = np.array(color_mean)
        #===================================================
        #===================================================
        self.last_batch_handle = last_batch_handle

    def _read(self):
        """get two list, each list contains two elements: name and nd.array 
value"""
        data = {}
        label = {}
        data[self.data_name], label[self.label_name] = self._read_img()
        return list(data.items()), list(label.items())

    def _read_img(self):
        # get next data file from the file name iterator
        img_name = self.img_data_iter.__next__()
        # open image file
        img = Image.open(os.path.join(self.dir_train, img_name))
        # find corresponding label image and open       [s for s in self.img_label_lst if img_name in s][0]
        label_name = img_name.split('.')[0] + '_mask.gif'
        label = Image.open(os.path.join(self.dir_label, label_name))
        # check image file size match
        assert img.size == label.size
        # convert into numpy array and manipulate, resulting 3d array: height, width, color
        img = np.array(img, dtype = np.float32)
        #===================================================
        #===================================================
        #img = img - self.weird.reshape(1,1,3)
        test = self.weird
        #===================================================
        #===================================================
        img = np.swapaxes(img, 0, 2)
        # (c, h, w)
        img = np.swapaxes(img, 1, 2)  
        # (1, c, h, w)
        img = np.expand_dims(img, axis=0)  
        # resulting 2d array: height, width
        label = np.array(label) 
        # (h, w)
        label = np.array(label)  
        # (1, h, w)
        label = np.expand_dims(label, axis=0)  
        return (img, label)

    def reset(self):
        self.cursor = -1
        self.img_data_iter = iter(self.img_data_lst)

    def iter_next(self):
        self.cursor += 1
        if (self.cursor < self.num_data - 1):
            return True
        else:
            return False

    def next(self):
        if self.iter_next():
            '''
            try:
                self.data, self.label = self._read()
                return {self.data_name  :  self.data[0][1],
                        self.label_name :  self.label[0][1]}
            except:
                raise
            '''
            self.data, self.label = self._read()
            return DataBatch(data = self.data, label = self.label, \
                    pad=self.getpad(), index=None)
        else:
            raise StopIteration

    @property
    def provide_data(self):
        """The name and shape of data provided by this iterator"""
        return [(k, tuple([1] + list(v.shape[1:]))) for k, v in self.data]

    @property
    def provide_label(self):
        """The name and shape of label provided by this iterator"""
        return [(k, tuple([1] + list(v.shape[1:]))) for k, v in self.label]

    def get_batch_size(self):
        return 1

截图：

调用函数中的class属性。

删除对class属性的调用，创建一个对象并直接访问相同的attribte。

Answer 1

您在定义之前尝试访问self.weird。

self.data, self.label = self._read()   
# self._read() calls self. _read_img() 
# which tries to access self.weird
# => AttributeError... 

#...     

# move this line above `self.data...`,
# and all should be well! 
self.weird = np.array(color_mean)

希望这有帮助！