diff --git a/python/chemiscope/explore.py b/python/chemiscope/explore.py
index b279444d4..8f253542f 100644
--- a/python/chemiscope/explore.py
+++ b/python/chemiscope/explore.py
@@ -110,10 +110,9 @@ def soap_kpca_featurize(frames, _environments):
 
     # Use default featurizer
     else:
-        centers = None
         if environments is not None:
-            centers, frames = _pick_env_frames(environments, frames)
-        X_reduced = soap_pca_featurize(frames, centers)
+            frames = [frames[env_index] for env_index, _, _ in environments]
+        X_reduced = soap_pca_featurize(frames, environments)
 
     # Add dimensionality reduction results to properties
     properties["features"] = X_reduced
@@ -122,7 +121,7 @@ def soap_kpca_featurize(frames, _environments):
     return show(frames=frames, properties=properties, mode=mode)
 
 
-def soap_pca_featurize(frames, centers=None):
+def soap_pca_featurize(frames, environments=None):
     """
     Computes SOAP features for a given set of atomic structures and performs
     dimensionality reduction using PCA. Custom featurize functions should
@@ -142,6 +141,12 @@ def soap_pca_featurize(frames, centers=None):
             f"Required package not found: {str(e)}. Please install dependency "
             + "using 'pip install chemiscope[explore]'."
         )
+    centers = None
+
+    # Get the atom indexes from the environments and pick related frames
+    if environments is not None:
+        centers = _extract_environment_indices(environments)
+
     # Get global species
     species = set()
     for frame in frames:
@@ -174,18 +179,16 @@ def soap_pca_featurize(frames, centers=None):
     return pca.fit_transform(feats)
 
 
-def _pick_env_frames(envs, frames):
+def _extract_environment_indices(envs):
     """
-    Get environment indices par structures and pick corresponding frames
+    Extract environment indices per structure
 
     :param: list envs: each element is a list of [env_index, atom_index, cutoff]
-    :param: list frames: list of frames
+    :return: dict of structure indices mapping to lists of atom indices
     """
     grouped_envs = {}
-    picked_frames = []
     for [env_index, atom_index, _cutoff] in envs:
         if env_index not in grouped_envs:
             grouped_envs[env_index] = []
         grouped_envs[env_index].append(atom_index)
-        picked_frames.append(frames[env_index])
-    return list(grouped_envs.values()), picked_frames
+    return list(grouped_envs.values())