From d940251d57f510f35e3d6754a5f25e0cc0a8577f Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Mon, 8 Mar 2021 09:45:18 +0100
Subject: [PATCH] PERF: get_dummies create array of 0/1s with appropriate
 layout for internals

---
 pandas/core/reshape/reshape.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/core/reshape/reshape.py b/pandas/core/reshape/reshape.py
index 271bb2ca8dd75..ddf9817edf1a9 100644
--- a/pandas/core/reshape/reshape.py
+++ b/pandas/core/reshape/reshape.py
@@ -1014,7 +1014,8 @@ def get_empty_frame(data) -> DataFrame:
         return out
 
     else:
-        dummy_mat = np.eye(number_of_cols, dtype=dtype).take(codes, axis=0)
+        # take on axis=1 + transpose to ensure ndarray layout is column-major
+        dummy_mat = np.eye(number_of_cols, dtype=dtype).take(codes, axis=1).T
 
         if not dummy_na:
             # reset NaN GH4446