diff --git a/pyFTS/partitioners/Util.py b/pyFTS/partitioners/Util.py
index ad40384..b96d529 100644
--- a/pyFTS/partitioners/Util.py
+++ b/pyFTS/partitioners/Util.py
@@ -24,13 +24,14 @@ def plot_sets(sets: dict, titles : list, size=[12, 10], save=False, file=None, a
     
     """
     num = len(sets)
+    num_cols_plot = 1
 
     if axis is None:
-        fig, axes = plt.subplots(nrows=num, ncols=1, figsize=size)
-    for k in np.arange(0,num):
+        fig, axes = plt.subplots(nrows=num, ncols=num_cols_plot, figsize=size, squeeze=False)
+    for k in range(num):
         ticks = []
         x = []
-        ax = axes[k] if axis is None else axis
+        ax = axes[k, num_cols_plot-1] if axis is None else axis
         ax.set_title(titles[k])
         ax.set_ylim([0, 1.1])
         for key in sets[k].keys():