OpenAI CartPole w/ Keras: Complete

cartpole.py

"""
__name__   = predict.py
__author__ = Yash Patel
__description__ = Full prediction code of OpenAI Cartpole environment using Keras
"""

import gym
import numpy as np
from keras.models import Sequential
from keras.layers import Dense, Dropout

def gather_data(env):
	num_trials = 10000
	min_score = 50
	sim_steps = 500
	trainingX, trainingY = [], []

	scores = []
	for _ in range(num_trials):
		observation = env.reset()
		score = 0
		training_sampleX, training_sampleY = [], []
		for step in range(sim_steps):
			# action corresponds to the previous observation so record before step
			action = np.random.randint(0, 2)
			one_hot_action = np.zeros(2)
			one_hot_action[action] = 1
			training_sampleX.append(observation)
			training_sampleY.append(one_hot_action)
			
			observation, reward, done, _ = env.step(action)
			score += reward
			if done:
				break
		if score > min_score:
			scores.append(score)
			trainingX += training_sampleX
			trainingY += training_sampleY

	trainingX, trainingY = np.array(trainingX), np.array(trainingY)
	print("Average: {}".format(np.mean(scores)))
	print("Median: {}".format(np.median(scores)))
	return trainingX, trainingY

def create_model():
	model = Sequential()
	model.add(Dense(128, input_shape=(4,), activation="relu"))
	model.add(Dropout(0.6))

	model.add(Dense(256, activation="relu"))
	model.add(Dropout(0.6))

	model.add(Dense(512, activation="relu"))
	model.add(Dropout(0.6))

	model.add(Dense(256, activation="relu"))
	model.add(Dropout(0.6))

	model.add(Dense(128, activation="relu"))
	model.add(Dropout(0.6))
	model.add(Dense(2, activation="softmax"))

	model.compile(
		loss="categorical_crossentropy",
		optimizer="adam",
		metrics=["accuracy"])
	return model

def predict():
	env = gym.make("CartPole-v0")
	trainingX, trainingY = gather_data(env)
	model = create_model()
	model.fit(trainingX, trainingY, epochs=5)
	
	scores = []
	num_trials = 50
	sim_steps = 500
	for _ in range(num_trials):
		observation = env.reset()
		score = 0
		for step in range(sim_steps):
			action = np.argmax(model.predict(observation.reshape(1,4)))
			observation, reward, done, _ = env.step(action)
			score += reward
			if done:
				break
		scores.append(score)

	print(np.mean(scores))

if __name__ == "__main__":
	predict()

I am facing this error, when I try to execute your code:

print(model.predict(prev_obs.reshape(-1, len(prev_obs), 1)))

AttributeError: 'NoneType' object has no attribute 'predict'

How do i eradicate this issue?