[MRG] Tqdm googcolab, Resolve #307 (#343)

* Change Process.Pool to subprocess to be compatible with google colab

* Add docstring for model_trainer and preprocessor

* Replace tqdm.notebook to tqdm for googcolab

autokeras/nn/model_trainer.py

@@ -6,7 +6,7 @@
 import numpy as np
 import torch
 from torchvision import utils as vutils
-from tqdm.autonotebook import tqdm
+from tqdm import tqdm
 from autokeras.constant import Constant
 from autokeras.utils import get_device
 

autokeras/preprocessor.py

@@ -100,6 +100,7 @@ def __call__(self, img):
 
 class DataTransformer(ABC):
     """A superclass for all the DataTransformer."""
+
     def __init__(self):
         pass
 
@@ -140,6 +141,7 @@ def text_transform(compose_list, data, targets):
 
 class TextDataTransformer(DataTransformer):
     """ A DataTransformer class for the text data."""
+
     def __init__(self):
         super().__init__()
 
@@ -303,6 +305,7 @@ def __len__(self):
 
 class BatchDataset(Dataset):
     """A torch.Dataset class that can read data batch by batch."""
+
     def __init__(self, csv_file_path, image_path, has_target=True):
         file_names, target = read_csv_file(csv_file_path)
 

autokeras/utils.py

@@ -47,7 +47,7 @@ def pickle_to_file(obj, path):
     """Save the pickle file to the specified path."""
     pickle.dump(obj, open(path, 'wb'))
 
-
+# TODO cannot detect nvidia-smi in Windows normally. We need a fall back for windows
 def get_device():
     """ If CUDA is available, use CUDA device, else use CPU device.