rlevo-environments 0.2.0

RL benchmark environments and landscapes for rlevo (internal crate — use `rlevo` for the full API)
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//! Action type for the [`super::Reacher`] environment.
//!
//! [`ReacherAction`] carries a 2-element `[shoulder, elbow]` torque command in
//! pre-gear units. The environment clips each element to `[-1.0, 1.0]` before
//! multiplying by the gear ratio (default `[200, 200]`) and applying the
//! resulting torques to the Rapier rigid bodies.

use burn::prelude::{Backend, Tensor};
use rlevo_core::action::ContinuousAction;
use rlevo_core::base::{Action, TensorConversionError, TensorConvertible};
use serde::{Deserialize, Serialize};

/// 2D continuous action — `[shoulder, elbow]` torque targets in
/// pre-gear units. Bounds: `[-1.0, 1.0]` per element.
#[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize)]
pub struct ReacherAction(pub [f32; 2]);

impl ReacherAction {
    /// Construct an action from explicit shoulder and elbow torque targets.
    ///
    /// Values outside `[-1.0, 1.0]` are accepted here but will be clamped by
    /// the environment before the gear ratio is applied. Prefer values in range
    /// to match the declared action space.
    #[must_use]
    pub const fn new(shoulder: f32, elbow: f32) -> Self {
        Self([shoulder, elbow])
    }
}

impl Action<1> for ReacherAction {
    fn shape() -> [usize; 1] {
        [2]
    }

    fn is_valid(&self) -> bool {
        self.0.iter().all(|v| v.is_finite() && v.abs() <= 1.0)
    }
}

impl ContinuousAction<1> for ReacherAction {
    /// Returns the raw `[shoulder, elbow]` slice.
    fn as_slice(&self) -> &[f32] {
        &self.0
    }

    /// Returns a new action with both elements clamped to `[min, max]`.
    fn clip(&self, min: f32, max: f32) -> Self {
        Self([self.0[0].clamp(min, max), self.0[1].clamp(min, max)])
    }

    /// Construct from a slice. The slice must contain at least two elements;
    /// only `values[0]` (shoulder) and `values[1]` (elbow) are read.
    fn from_slice(values: &[f32]) -> Self {
        Self([values[0], values[1]])
    }

    /// Sample a uniformly-random action in `[-1.0, 1.0]²` using the global
    /// thread-local RNG.
    fn random() -> Self {
        Self([
            rand::random::<f32>() * 2.0 - 1.0,
            rand::random::<f32>() * 2.0 - 1.0,
        ])
    }
}

impl<B: Backend> TensorConvertible<1, B> for ReacherAction {
    fn to_tensor(&self, device: &<B as burn::tensor::backend::BackendTypes>::Device) -> Tensor<B, 1> {
        Tensor::from_floats(self.0, device)
    }

    fn from_tensor(tensor: Tensor<B, 1>) -> Result<Self, TensorConversionError> {
        let data = tensor.into_data();
        let slice = data.as_slice::<f32>().map_err(|e| TensorConversionError {
            message: format!("expected f32 action tensor: {e:?}"),
        })?;
        if slice.len() != 2 {
            return Err(TensorConversionError {
                message: format!("expected 2 action elements, got {}", slice.len()),
            });
        }
        Ok(Self([slice[0], slice[1]]))
    }
}