From a74d40c1254b5672b122f810e4b4dcf344cf00c6 Mon Sep 17 00:00:00 2001
From: zhi-bao <tomk12171217@gmail.com>
Date: Tue, 10 Dec 2024 18:10:15 +0800
Subject: [PATCH] Avoid additional memory usage when performing hstack to csr
 format.

---
 libmultilabel/linear/tree.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libmultilabel/linear/tree.py b/libmultilabel/linear/tree.py
index c33cfe33..0ad33f3f 100644
--- a/libmultilabel/linear/tree.py
+++ b/libmultilabel/linear/tree.py
@@ -284,7 +284,7 @@ def visit(node):
 
     model = linear.FlatModel(
         name="flattened-tree",
-        weights=sparse.hstack(weights, "csr"),
+        weights=sparse.hstack(weights, "csc"),
         bias=bias,
         thresholds=0,
         multiclass=False,