Fix torch imports for rpi (#1004)

* Moving torch imports into functions such that donkeycar can continue to work w/o pytorch installation. This is the default setup on RPi.

* Bumped version

(cherry picked from commit 14db8a8)

donkeycar/parts/interpreter.py

@@ -5,7 +5,6 @@
 from typing import Union, Sequence, List
 
 import tensorflow as tf
-import torch
 from tensorflow import keras
 
 from tensorflow.python.framework.convert_to_constants import \
@@ -171,6 +170,7 @@ def load_weights(self, model_path: str, by_name: bool = True) -> \
     def summary(self) -> str:
         return self.model.summary()
 
+
 class FastAIInterpreter(Interpreter):
 
     def __init__(self):
@@ -206,14 +206,15 @@ def invoke(self, inputs):
 
     def predict(self, img_arr: np.ndarray, other_arr: np.ndarray) \
             -> Sequence[Union[float, np.ndarray]]:
-
+        import torch
         inputs = torch.unsqueeze(img_arr, 0)
         if other_arr is not None:
             #other_arr = np.expand_dims(other_arr, axis=0)
             inputs = [img_arr, other_arr]
         return self.invoke(inputs)
 
     def load(self, model_path: str) -> None:
+        import torch
         logger.info(f'Loading model {model_path}')
         if torch.cuda.is_available():
             logger.info("using cuda for torch inference")
@@ -228,6 +229,7 @@ def load(self, model_path: str) -> None:
     def summary(self) -> str:
         return self.model
 
+
 class TfLite(Interpreter):
     """
     This class wraps around the TensorFlow Lite interpreter.

donkeycar/utils.py

@@ -439,8 +439,6 @@ def get_model_by_type(model_type: str, cfg: 'Config') -> Union['KerasPilot', 'Fa
     from donkeycar.parts.interpreter import KerasInterpreter, TfLite, TensorRT, \
         FastAIInterpreter
 
-    from donkeycar.parts.fastai import FastAILinear
-
     if model_type is None:
         model_type = cfg.DEFAULT_MODEL_TYPE
     logger.info(f'get_model_by_type: model type is: {model_type}')
@@ -455,6 +453,7 @@ def get_model_by_type(model_type: str, cfg: 'Config') -> Union['KerasPilot', 'Fa
         interpreter = FastAIInterpreter()
         used_model_type = model_type.replace('fastai_', '')
         if used_model_type == "linear":
+            from donkeycar.parts.fastai import FastAILinear
             return FastAILinear(interpreter=interpreter, input_shape=input_shape)
     else:
         interpreter = KerasInterpreter()