Integrate modules from road-gen that are needed for segmented road generation

src/road_gen/generators/base_road_generator.py

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+import secrets
+
+import numpy as np
+
+
+class BaseRoadGenerator:
+    """A base generator object for generating a road of a specified length."""
+    def __init__(
+            self,
+            length: int | float,
+            ds: int | float,
+            velocity: int | float,
+            mu: float = 0.7,
+            g: float = 9.81,
+            seed: int | None = None
+            ):
+        """Initialize a BaseGenerator with a given or random seed.
+
+        Args:
+            length (int | float): The total length of the road in meters.
+            ds (int | float): The step size in meters.
+            velocity (int | float): Velocity in meters per second.
+            mu (float): Coefficient of friction. Defaults to 0.7 (dry asphalt).
+            g (float): Acceleration due to gravity (m/s^2). Defaults to 9.81.
+            seed (int | None, optional): Set a seed for the generator.
+                Defaults to a random seed.
+        """
+        if seed is None:
+            seed = secrets.randbits(32)
+
+        if not isinstance(seed, int):
+            raise TypeError("seed must be an integer or None.")
+
+        if not isinstance(length, int | float):
+            raise TypeError("Length must be an integer or float in meters.")
+
+        if not isinstance(ds, int | float):
+            raise TypeError("Step size must be integer or float in meters.")
+
+        if not isinstance(velocity, int | float):
+            raise TypeError(
+                "Velocity must be integer or float in meters per second."
+            )
+
+        self.length = length
+        self.ds = ds
+
+        self.velocity = velocity
+        self.min_radius = (velocity ** 2) / (g * mu)
+
+        self.seed = seed
+        self._rng = np.random.default_rng(seed)
+
+    def generate(self):
+        pass

src/road_gen/generators/segmented_road_generator.py

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+from typing import Tuple
+
+import numpy as np
+
+from .base_road_generator import BaseRoadGenerator
+from road_gen.prefabs import prefabs
+from road_gen.integrator.integrator import integrate_road
+
+
+class SegmentedRoadGenerator(BaseRoadGenerator):
+    def __init__(
+        self,
+        length: int | float,
+        ds: int | float,
+        velocity: int | float,
+        mu: float = 0.7,
+        g: float = 9.81,
+        seed: int | None = None
+    ):
+        """Initialize a SegmentedRoadGenerator with given or random seed.
+
+        Args:
+            length (int | float): The total length of the road in meters.
+            ds (int | float): The step size in meters.
+            velocity (int | float): Velocity in meters per second.
+            mu (float): Coefficient of friction. Defaults to 0.7 (dry asphalt).
+            g (float): Acceleration due to gravity (m/s^2). Defaults to 9.81.
+            seed (int | None, optional): Set a seed for the generator.
+                Defaults to random seed.
+        """
+
+        super().__init__(length, ds, velocity, mu, g, seed)
+
+    def generate(
+            self,
+            segments: list[str],
+            alpha: float = 100,
+            min_turn_angle: float = 15.,
+            max_turn_angle: float = 90.
+    ) -> Tuple[np.ndarray, np.ndarray]:
+        """Generate a curvature profile from a list of segments.
+
+        Args:
+            segments (list[str]): List of segments.
+            alpha (float, optional): Dirichlet concentration parameter.
+                A higher value leads to more uniform apportionment of the
+                length amongst the segments, while a lower value allows more
+                random apportionment. Defaults to 1.0.
+            min_turn_angle (float, optional): Minimum turn angle in degrees for
+                random sampling of turn radius. Does nothing if `angle_list` is
+                provided or no `turn_*` segement is specified in the `segments`
+                list.
+            min_turn_angle (float, optional): Maximum turn angle in degrees for
+                random sampling of turn radius. Does nothing if `angle_list` is
+                provided or no `turn_*` segement is specified in the `segments`
+                list.
+        Raises:
+            ValueError: Raised when a turn
+                is too tight given its segment length and the velocity.
+                To fix this, you can try to reduce the amount of segments or
+                increase length. Increasing alpha
+                (Dirichlet concentration parameter) can also help because this
+                reduces the odds of very small lengths being assigned to
+                turn segments.
+
+        Returns:
+            Tuple[np.ndarray, np.ndarray]: x and y coordinates of the
+                waypoints describing the random road.
+        """
+        existing_prefabs = prefabs.PREFABS.keys()
+        if not all(segment in existing_prefabs for segment in segments):
+            raise ValueError(
+                "Invalid segment type provided. Available choices"
+                f"{existing_prefabs}"
+            )
+
+        self.segments = segments
+        self.alpha = alpha
+        num_points = int(self.length / self.ds)
+
+        # divide num_points into len(segments) randomly sized parts.
+        parts = self._rng.dirichlet(np.full(len(segments), alpha), size=1)[0]
+        parts = parts * num_points
+        parts = np.round(parts).astype(int)
+
+        # correct round off so the sum of parts is still total length L.
+        if sum(parts) != num_points:
+            parts[0] += num_points - sum(parts)
+
+        curvature = np.zeros(num_points)
+        current_index = 0
+
+        for seg_name, seg_length in zip(segments, parts):
+            seg_function = prefabs.PREFABS[seg_name]
+
+            if seg_name == 'straight':
+                curvature_s = seg_function(seg_length)
+            else:
+                R_min_angle = seg_length / np.deg2rad(max_turn_angle)
+                R_max_angle = seg_length / np.deg2rad(min_turn_angle)
+
+                # physics limit
+                R_min = max(self.min_radius, R_min_angle)
+
+                if R_min > R_max_angle:
+                    raise ValueError("No valid radius for this turn segment")
+
+                rand_radius = self._rng.uniform(R_min, R_max_angle)
+
+                if seg_name.startswith("u_turn"):
+                    curvature_s = seg_function(rand_radius)
+                else:
+                    curvature_s = seg_function(seg_length, rand_radius)
+
+            curvature[current_index:(current_index + seg_length)] = curvature_s
+            current_index += seg_length
+
+            x, y = integrate_road(curvature)
+
+        return x * self.ds, y * self.ds

src/road_gen/prefabs/prefabs.py

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+import numpy as np
+
+
+def straight(length: int) -> np.ndarray:
+    return np.zeros(length)
+
+
+def turn_left(length: int, radius: float) -> np.ndarray:
+    return np.full(length, 1.0 / radius)
+
+
+def turn_right(length: int, radius: float) -> np.ndarray:
+    return -turn_left(length, radius)
+
+
+PREFABS = {
+    'straight': straight,
+    'turn_left': turn_left,
+    'turn_right': turn_right,
+}