fix(zigzag): skip minmax normalization with single valid value

diff --git a/quickadapter/user_data/strategies/Utils.py b/quickadapter/user_data/strategies/Utils.py
index 70327d188d713efdf319c5ab79967ae025f7ae6a..d7292c286f04673f1817e71c475f28705da78a99 100644 (file)
--- a/quickadapter/user_data/strategies/Utils.py
+++ b/quickadapter/user_data/strategies/Utils.py
@@ -1738,7 +1738,8 @@ def zigzag(
 
         arr = np.asarray(values, dtype=float)
         valid_mask = np.isfinite(arr)
-        if not valid_mask.any():
+        n_valid = valid_mask.sum()
+        if n_valid < 2:
             return values
 
         min_val = np.nanmin(arr)