fixed centroid generation bugs. all cvtarchive tests passed.

ribs/archives/_cvt_archive.py

@@ -214,17 +214,27 @@ def __init__(self,
             elif centroid_method == "sobol":
                 # Generate self._cells number of centroids as a Sobol sequence.
                 sampler = Sobol(d=self._measure_dim, scramble=False)
-                num_points = np.log2(self._cells).astype(int)
-                self._centroids = sampler.random_base2(num_points)
+                sobol_nums = sampler.random(n=self._cells)
+                lower = self._lower_bounds
+                upper = self._upper_bounds
+                scaled_sobol_nums = lower + sobol_nums * (upper - lower)
+                self._centroids = scaled_sobol_nums
             elif centroid_method == "scrambled_sobol":
                 # Generates centroids as a scrambled Sobol sequence.
                 sampler = Sobol(d=self._measure_dim, scramble=True)
-                num_points = np.log2(self._cells).astype(int)
-                self._centroids = sampler.random_base2(num_points)
+                sobol_nums = sampler.random(n=self._cells)
+                lower = self._lower_bounds
+                upper = self._upper_bounds
+                scaled_sobol_nums = lower + sobol_nums * (upper - lower)
+                self._centroids = scaled_sobol_nums
             elif centroid_method == "halton":
                 # Generates centroids using a Halton sequence.
                 sampler = Halton(d=self._measure_dim)
-                self._centroids = sampler.random(n=self._cells)
+                halton_nums = sampler.random(n=self._cells)
+                lower = self._lower_bounds
+                upper = self._upper_bounds
+                scaled_halton_nums = lower + halton_nums * (upper - lower)
+                self._centroids = scaled_halton_nums
         else:
             # Validate shape of `custom_centroids` when they are provided.
             custom_centroids = np.asarray(custom_centroids, dtype=self.dtype)