Resampling index error appears to be gone. Still need more dialing in.

ch-13/4.3-monte-carlo_perf/resample.py

@@ -0,0 +1,23 @@
+import numpy as np
+import random
+
+
+def resample(weights, sample_count):
+    """Return sample_count number of samples from the
+    poses, based on the weights array.
+    Uses low variance resampling"""
+    samples = np.zeros((sample_count, 3))
+    interval = np.sum(weights) / sample_count
+    shift = random.uniform(0, interval)
+    cumulative_weights = weights[0]
+    source_index = 0
+    for current_index in range(sample_count):
+        weight_index = shift + current_index * interval
+        while weight_index >= cumulative_weights:
+            source_index += 1
+            source_index = min(len(weights), source_index)
+            cumulative_weights += weights[source_index]
+        samples[current_index] = source_index
+    if samples.shape[0] != sample_count:
+        raise Exception("Sample count mismatch in resample.")
+    return samples