From a85c17727fc573f1d0cc2e993792a8694eac581e Mon Sep 17 00:00:00 2001
From: jaimefrio <jaime.frio@gmail.com>
Date: Wed, 27 Aug 2014 22:52:19 -0700
Subject: ENH: Speed up `unique` with `return_inverse`

This replaces a sort with fancy indexing.
---
 numpy/lib/arraysetops.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

(limited to 'numpy/lib/arraysetops.py')

diff --git a/numpy/lib/arraysetops.py b/numpy/lib/arraysetops.py
index 2d98c35d2..5ace7146a 100644
--- a/numpy/lib/arraysetops.py
+++ b/numpy/lib/arraysetops.py
@@ -204,8 +204,9 @@ def unique(ar, return_index=False, return_inverse=False, return_counts=False):
             ret += (perm[flag],)
         if return_inverse:
             iflag = np.cumsum(flag) - 1
-            iperm = perm.argsort()
-            ret += (np.take(iflag, iperm),)
+            inv_idx = np.empty_like(ar, dtype=np.intp)
+            inv_idx[perm] = iflag
+            ret += (inv_idx,)
         if return_counts:
             idx = np.concatenate(np.nonzero(flag) + ([ar.size],))
             ret += (np.diff(idx),)
-- 
cgit v1.2.1