Data preparation

In the Atari environment, recall that there are three modes for each Atari game, for example, Breakout, BreakoutDeterministic, and BreakoutNoFrameskip, and each mode has two versions, for example, Breakout-v0 and Breakout-v4. The main difference between the three modes is the frameskip parameter that indicates the number of frames (steps) the one action is repeated on. This is called the frame-skipping technique, which allows us to play more games without significantly increasing the runtime.

However, in the Minecraft environment, there is only one mode where the frameskip parameter is equal to one. Therefore, in order to apply the frame-skipping technique, we need to explicitly repeat a certain action frameskip multiple times during one timestep. Besides this, the frame images returned by the step function are RGB images. Similar to the Atari environment, the observed frame images are converted to grayscale and then resized to 84x84. The following code provides the wrapper...