Gymnasium/docs/environments/atari/private_eye.md

---
title: PrivateEye
---

# PrivateEye

```{figure} ../../_static/videos/atari/private_eye.gif
:width: 120px
:name: PrivateEye
```

This environment is part of the <a href='..'>Atari environments</a>. Please read that page first for general information.

|   |   |
|---|---|
| Action Space | Discrete(18) |
| Observation Space | Box(0, 255, (210, 160, 3), uint8) |
| Import | `gymnasium.make("ALE/PrivateEye-v5")` |

For more PrivateEye variants with different observation and action spaces, see the variants section.

## Description

You control the French Private Eye Pierre Touche. Navigate the city streets, parks, secret passages, dead-ends and one-ways in search of the ringleader, Henri Le Fiend and his gang. You also need to find evidence and stolen goods that are scattered about. There are five cases, complete each case before its statute of limitations expires.

For a more detailed documentation, see [the AtariAge page](https://atariage.com/manual_html_page.php?SoftwareLabelID=376)

## Actions

PrivateEye has the action space `Discrete(18)` with the table below listing the meaning of each action's meanings.
As PrivateEye uses the full set of actions then specifying `full_action_space=True` will not modify the action space of the environment if passed to `gymnasium.make`.

| Value   | Meaning      | Value   | Meaning         | Value   | Meaning        |
|---------|--------------|---------|-----------------|---------|----------------|
| `0`     | `NOOP`       | `1`     | `FIRE`          | `2`     | `UP`           |
| `3`     | `RIGHT`      | `4`     | `LEFT`          | `5`     | `DOWN`         |
| `6`     | `UPRIGHT`    | `7`     | `UPLEFT`        | `8`     | `DOWNRIGHT`    |
| `9`     | `DOWNLEFT`   | `10`    | `UPFIRE`        | `11`    | `RIGHTFIRE`    |
| `12`    | `LEFTFIRE`   | `13`    | `DOWNFIRE`      | `14`    | `UPRIGHTFIRE`  |
| `15`    | `UPLEFTFIRE` | `16`    | `DOWNRIGHTFIRE` | `17`    | `DOWNLEFTFIRE` |

## Observations

Atari environments have three possible observation types: `"rgb"`, `"grayscale"` and `"ram"`.

- `obs_type="rgb" -> observation_space=Box(0, 255, (210, 160, 3), np.uint8)`
- `obs_type="ram" -> observation_space=Box(0, 255, (128,), np.uint8)`
- `obs_type="grayscale" -> Box(0, 255, (210, 160), np.uint8)`, a grayscale version of the "rgb" type

See variants section for the type of observation used by each environment id by default.

### Rewards

You score points for completing your tasks like gathering evidence, nabbing questionable characters or closing cases etc. You lose points if you get hit or if your auto is on a pothole.
For a more detailed documentation, see [the AtariAge page](https://atariage.com/manual_html_page.php?SoftwareLabelID=376).

## Variants

PrivateEye has the following variants of the environment id which have the following differences in observation,
the number of frame-skips and the repeat action probability.

| Env-id                         | obs_type=   | frameskip=   | repeat_action_probability=   |
|--------------------------------|-------------|--------------|------------------------------|
| PrivateEye-v0                  | `"rgb"`     | `(2, 5)`     | `0.25`                       |
| PrivateEye-ram-v0              | `"ram"`     | `(2, 5)`     | `0.25`                       |
| PrivateEye-ramDeterministic-v0 | `"ram"`     | `4`          | `0.25`                       |
| PrivateEye-ramNoFrameskip-v0   | `"ram"`     | `1`          | `0.25`                       |
| PrivateEyeDeterministic-v0     | `"rgb"`     | `4`          | `0.25`                       |
| PrivateEyeNoFrameskip-v0       | `"rgb"`     | `1`          | `0.25`                       |
| PrivateEye-v4                  | `"rgb"`     | `(2, 5)`     | `0.0`                        |
| PrivateEye-ram-v4              | `"ram"`     | `(2, 5)`     | `0.0`                        |
| PrivateEye-ramDeterministic-v4 | `"ram"`     | `4`          | `0.0`                        |
| PrivateEye-ramNoFrameskip-v4   | `"ram"`     | `1`          | `0.0`                        |
| PrivateEyeDeterministic-v4     | `"rgb"`     | `4`          | `0.0`                        |
| PrivateEyeNoFrameskip-v4       | `"rgb"`     | `1`          | `0.0`                        |
| ALE/PrivateEye-v5              | `"rgb"`     | `4`          | `0.25`                       |
| ALE/PrivateEye-ram-v5          | `"ram"`     | `4`          | `0.25`                       |

## Difficulty and modes

It is possible to specify various flavors of the environment via the keyword arguments `difficulty` and `mode`.
A flavor is a combination of a game mode and a difficulty setting. The table below lists the possible difficulty and mode values
along with the default values.

| Available Modes   | Default Mode   | Available Difficulties   | Default Difficulty   |
|-------------------|----------------|--------------------------|----------------------|
| `[0, 1, 2, 3, 4]` | `0`            | `[0, 1, 2, 3]`           | `0`                  |

## Version History

A thorough discussion of the intricate differences between the versions and configurations can be found in the general article on Atari environments.

* v5: Stickiness was added back and stochastic frameskipping was removed. The environments are now in the "ALE" namespace.
* v4: Stickiness of actions was removed
* v0: Initial versions release