reorganize to flat package structure

particlecloud/stuff.py

@@ -0,0 +1,33 @@
+class Particle:
+    def __init__(self, mass=1.0, velocity=None, position=None):
+        self.mass = mass
+        self.velocity = list(velocity if velocity is not None else [0.0, 0.0, 0.0])
+        self.position = list(position if position is not None else [0.0, 0.0, 0.0])
+
+    def __repr__(self):
+        return f"Particle(mass={self.mass}, velocity={self.velocity}, position={self.position})"
+
+
+class cloud:
+    def __init__(self, particles=None):
+        self.particles = list(particles or [])
+
+    def add(self, p):
+        self.particles.append(p)
+
+    def step(self, dt=1.0):
+        for p in self.particles:
+            p.position = [x + v * dt for x, v in zip(p.position, p.velocity)]
+        return self
+
+    def center(self):
+        total = sum(p.mass for p in self.particles)
+        if total == 0:
+            return [0.0, 0.0, 0.0]
+        answer = [0.0, 0.0, 0.0]
+        for p in self.particles:
+            answer = [a + p.mass * x for a, x in zip(answer, p.position)]
+        return [x / total for x in answer]
+
+    def __repr__(self):
+        return f"cloud({self.particles})"