From 0dd0fa7938f605833c85084f7f184445ca0b6fee Mon Sep 17 00:00:00 2001
From: Glenn Jocher <glenn.jocher@ultralytics.com>
Date: Tue, 3 Dec 2019 13:34:22 -0800
Subject: [PATCH] updates

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

diff --git a/utils/utils.py b/utils/utils.py
index ae02b9f99d..f7b8018725 100755
--- a/utils/utils.py
+++ b/utils/utils.py
@@ -449,7 +449,8 @@ def build_targets(model, targets):
         # Class
         tcls.append(c)
         if c.shape[0]:  # if any targets
-            assert c.max() <= model.nc, 'Target classes exceed model classes'
+            assert c.max() <= model.nc, 'Model accepts %g classes labeled from 0-%g, however you supplied a label %g. \
+                See https://github.com/ultralytics/yolov3/wiki/Train-Custom-Data' % (model.nc, model.nc - 1, c.max())
 
     return tcls, tbox, indices, av