From 66be8deee190f4c9fac7158378d34a3ff065df64 Mon Sep 17 00:00:00 2001
From: William Silversmith <william.silversmith@gmail.com>
Date: Mon, 25 Nov 2024 21:33:21 -0500
Subject: [PATCH] perf(dust): multiply operation was more expensive than
 assignment

---
 cc3d/__init__.py | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/cc3d/__init__.py b/cc3d/__init__.py
index f7b7e8c..91c0025 100644
--- a/cc3d/__init__.py
+++ b/cc3d/__init__.py
@@ -63,21 +63,16 @@ def dust(
   mask_sizes = stats["voxel_counts"]
   del stats
 
-  if invert:
-    to_retain = [ 
-      i for i in range(1, N+1) if mask_sizes[i] < threshold 
-    ]
-  else:
-    to_retain = [ 
-      i for i in range(1, N+1) if mask_sizes[i] >= threshold 
-    ]
+  to_mask = [ 
+    i for i in range(1, N+1) if mask_sizes[i] < threshold 
+  ]
 
-  if len(to_retain) == N:
+  if len(to_mask) == 0:
     return img
 
-  mask = np.isin(cc_labels, to_retain, assume_unique=True)
+  mask = np.isin(cc_labels, to_mask, assume_unique=True, invert=False)
   del cc_labels
-  img *= mask
+  img[mask] = 0
   return img.view(orig_dtype)
 
 def largest_k(