AttributeError: 'Sequential' object has no attribute '_compile_time_distribution_strategy'

Question

I'm trying to train an agent using TensorFlow and Keras-rl2 to be able to play a gym environment called CartPole-v1 and I'm using google colaboratory this's my implementation:

!pip install gym[classic_control]
!pip install keras-rl2
import tensorflow as tf 
from tensorflow import keras as k
import numpy as np
import gym 
import random
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense, Flatten
from tensorflow.keras.optimizers import Adam

env = gym.make('CartPole-v1')
states = env.observation_space.shape[0]
actions = env.action_space.n #actions = 2

def build_model(states, actions):
    model = Sequential()
    model.add(Flatten(input_shape=(1,states)))
    model.add(Dense(24, activation='relu'))
    model.add(Dense(24, activation='relu'))
    model.add(Dense(actions, activation='linear'))
    return model

model = build_model(states, actions)
model.summary()

from rl.agents import DQNAgent
from rl.policy import BoltzmannQPolicy
from rl.memory import SequentialMemory

def build_agent(model, actions):
    policy = BoltzmannQPolicy()
    memory = SequentialMemory(limit=50000, window_length=1)
    dqn = DQNAgent(model=model, memory=memory, policy=policy, 
                  nb_actions=actions, nb_steps_warmup=10, target_model_update=1e-2)
    return dqn


dqn = build_agent(model, actions)
dqn.compile(Adam(lr=1e-3), metrics=['mae']) # this's the line that is problematic
dqn.fit(env, nb_steps=50000, visualize=False, verbose=1)

I get this Error when I try to compile my DQN agent:

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-35-08c9e140f6bc> in <module>
      1 dqn = build_agent(model, actions)
----> 2 dqn.compile(Adam(lr=1e-3), metrics=['mae'])
      3 dqn.fit(env, nb_steps=50000, visualize=False, verbose=1)

2 frames
/usr/local/lib/python3.8/dist-packages/keras/engine/training_v1.py in get_weights(self)
    154     """
    155     strategy = (self._distribution_strategy or
--> 156                 self._compile_time_distribution_strategy)
    157     if strategy:
    158       with strategy.scope():

AttributeError: 'Sequential' object has no attribute '_compile_time_distribution_strategy'

I tried searching for a solution on the internet but I couldn't find any I did find someone with a similar problem but he was building the model before importing the dependencies but this wasn't the problem in my case

Answer 1

As you can see it here:

This will occur when you construct your model and then import from rl.* afterwards.

Reverse the order to this, and it will work:

!pip install gym[classic_control]
!pip install keras-rl2
import tensorflow as tf 
from tensorflow import keras as k
import numpy as np
import gym 
import random
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense, Flatten
from tensorflow.keras.optimizers import Adam


from rl.agents import DQNAgent
from rl.policy import BoltzmannQPolicy
from rl.memory import SequentialMemory

env = gym.make('CartPole-v1')
states = env.observation_space.shape[0]
actions = env.action_space.n #actions = 2