1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62

extern crate cpython;

use cpython::{ PyObject, ObjectProtocol, ToPyObject, NoArgs };
pub use cpython::{ Python, PyResult, PyDict };

macro_rules! call {
($obj:expr, $py:expr, $name:expr, $args:expr) => {
    $obj.call_method($py, $name, $args, None).unwrap()
}
}

pub struct Env<'a> {
    obj: PyObject,
    py: Python<'a>
}

impl<'a> Env<'a> {
    pub fn make(py: Python<'a>, game_id: &str) -> Env<'a> {
        py.run("import sys\nsys.argv = ['']", None, None).unwrap();
        Env {
            obj: py.import("gym").unwrap()
                .call(py, "make", (game_id, ), None).unwrap(),
            py
        }
    }

    pub fn reset(&self) -> Vec<f64> {
        let multi_list: PyObject = call!(self.obj, self.py, "reset", NoArgs {});
        self.py.import("numpy").unwrap()
            .call(self.py, "ravel", (multi_list, ), None).unwrap()
            .extract(self.py).unwrap()
    }

    pub fn step<T: ToPyObject>(&self, action: T) -> (Vec<f64>, f64, bool, PyDict) {
        call!(self.obj, self.py, "step", (action,)).extract(self.py).unwrap()
    }

    pub fn render(&self) {
        call!(self.obj, self.py, "render", NoArgs);
    }
}

#[cfg(test)]
mod tests {
    use ::Env;
    use cpython::Python;

    #[test]
    fn make_env() {
        let gil = Python::acquire_gil();

        let env = Env::make(gil.python(), "LunarLander-v2");

        env.reset();
        for _ in 0..1000 {
            env.render();
            if env.step(1).2 {
                env.reset();
            }
        }
    }
}