Initial commit

src/road_gen/generators/base_road_generator.py

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+import numpy as np
+import secrets
+
+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. Default is a random seed.
+        """        
+        if seed == 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/random_road_generator.py

@@ -0,0 +1,70 @@
+from typing import Tuple
+import numpy as np
+
+from .base_road_generator import BaseRoadGenerator
+from ..integrator.integrator import integrate_road
+
+class RandomRoadGenerator(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 RandomRoadGenerator 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. Default is a random seed.
+        """
+
+        super().__init__(length, ds, velocity, mu, g, seed)
+
+    def generate(
+            self,
+            straight_section_prob: float = 0.05,
+            straight_section_max_rel_size: float = 0.1
+    ) -> Tuple[np.ndarray, np.ndarray]:
+        """Generate a random road according to specified parameters.
+
+        Args:
+            straight_section_prob (float, optional): Probability at every step i that a straight section will start. Defaults to 0.05.
+            straight_section_max_rel_size (float, optional): The maximum size that straight section(s) can have relative to the total length of the path. Defaults to 0.1.
+
+        Returns:
+            Tuple[np.ndarray, np.ndarray]: x and y coordinates of the waypoints describing the random road.
+        """
+        
+        self.straight_section_prob = straight_section_prob
+        self.straight_section_max_rel_size = straight_section_max_rel_size
+        
+        num_points = int(self.length / (self.ds))
+        max_curvature = 1 / self.min_radius
+        
+        white_noise = self._rng.standard_normal(num_points)
+        curvature = np.clip(white_noise, -max_curvature, max_curvature)
+
+        # Randomly add multiple straight sections
+        i = 0
+        while i < num_points:
+            if np.random.rand() < straight_section_prob:
+                # Random straight segment length
+                max_len = int(num_points * straight_section_max_rel_size)
+                seg_len = np.random.randint(1, max_len + 1)
+                curvature[i:i+seg_len] = 0  # set curvature to zero for straight
+                i += seg_len  # skip over straight segment
+            else:
+                i += 1
+
+        x, y = integrate_road(curvature)
+
+        return x * self.ds, y * self.ds
+       

src/road_gen/generators/segmented_road_generator.py

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+from typing import Tuple
+
+import numpy as np
+from matplotlib import pyplot as plt
+
+from .base_road_generator import BaseRoadGenerator
+from ..prefabs import prefabs
+from ..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. Default is a random seed.
+        """
+
+        super().__init__(length, ds, velocity, mu, g, seed)
+
+    def generate(
+            self,
+            segments: list[str],
+            alpha: float = 1.0
+    ) -> Tuple[np.ndarray, np.ndarray]:
+        """Generate a curvature profile from a list of segments.
+
+        Args:
+            segments (list[str]): List of segments.
+            length (int): Total length of the path in meters.
+            velocity (float): Velocity of the car in km/h.
+            ds (float, optional): Step size. Defaults to 1.0.
+            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.
+
+        Raises:
+            ValueError: _description_
+            ValueError: _description_
+
+        Returns:
+            np.ndarray: _description_
+        """
+        if not all(segment in prefabs.PREFABS.keys() for segment in segments):
+            raise ValueError(f"Invalid segment type provided. Available choices: {prefabs.SEGMENTS.keys()}")
+        
+        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.pi / 2)
+                R_max_angle = seg_length / (np.pi / 6)
+
+                # 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 = np.random.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