imporve nomalize weight function

Author: AtsushiSakai

SLAM/FastSLAM1/fast_slam1.py

@@ -60,15 +60,15 @@ def normalize_weight(particles):
 
     sumw = sum([p.w for p in particles])
 
-    if sumw <= 0.0000001:
+    try:
+        for i in range(N_PARTICLE):
+            particles[i].w /= sumw
+    except ZeroDivisionError:
         for i in range(N_PARTICLE):
             particles[i].w = 1.0 / N_PARTICLE
 
         return particles
 
-    for i in range(N_PARTICLE):
-        particles[i].w /= sumw
-
     return particles