這部分課程我不明白這段代碼做了什么：for file in os.listdir(path):    if(os.path.isfile(os.path.join(path,file)) and select in file):         temp = scipy.io.loadmat(os.path.join(path,file))        temp = {k:v for k, v in temp.items() if k[0] != '_'}        for i  in range(len(temp[patch_type+"_patches"])):            self.tensors.append(temp[patch_type+"_patches"][i])            self.labels.append(temp[patch_type+"_labels"][0][i])self.tensors = np.array(self.tensors)self.labels = np.array(self.labels)尤其是這一行：temp = {k:v for k, v in temp.items() if k[0] != '_'}全班如下：class Datasets(Dataset):    def __init__(self,path,train,transform=None):        if(train):            select ="Training"            patch_type = "train"        else:            select = "Testing"            patch_type = "testing"        self.tensors = []        self.labels = []        self.transform = transform        for file in os.listdir(path):            if(os.path.isfile(os.path.join(path,file)) and select in file):                 temp = scipy.io.loadmat(os.path.join(path,file))                temp = {k:v for k, v in temp.items() if k[0] != '_'}                for i  in range(len(temp[patch_type+"_patches"])):                    self.tensors.append(temp[patch_type+"_patches"][i])                    self.labels.append(temp[patch_type+"_labels"][0][i])        self.tensors = np.array(self.tensors)        self.labels = np.array(self.labels)    def __len__(self):        try:            if len(self.tensors) != len(self.labels):                raise Exception("Lengths of the tensor and labels list are not the same")        except Exception as e:            print(e.args[0])        return len(self.tensors)    def __getitem__(self,idx):        sample = (self.tensors[idx],self.labels[idx])       # print(self.labels)        sample = (torch.from_numpy(self.tensors[idx]),torch.from_numpy(np.array(self.labels[idx])).long())        return sample    #tuple containing the image patch and its corresponding label