code change based on reviews

Author: charlesdong1991

pandas/core/internals/managers.py

@@ -1973,12 +1973,22 @@ def items_overlap_with_suffix(left, lsuffix, right, rsuffix):
 
         def lrenamer(x):
             if x in to_rename:
-                return '{x}{lsuffix}'.format(x=x, lsuffix=lsuffix)
+                if lsuffix is None and isinstance(x, str):
+                    return '{x}{lsuffix}'.format(x=x, lsuffix='')
+                elif lsuffix is None and isinstance(x, (float, int)):
+                    return x
+                else:
+                    return '{x}{lsuffix}'.format(x=x, lsuffix=lsuffix)
             return x
 
         def rrenamer(x):
             if x in to_rename:
-                return '{x}{rsuffix}'.format(x=x, rsuffix=rsuffix)
+                if rsuffix is None and isinstance(x, str):
+                    return '{x}{rsuffix}'.format(x=x, rsuffix='')
+                elif rsuffix is None and isinstance(x, (float, int)):
+                    return x
+                else:
+                    return '{x}{rsuffix}'.format(x=x, rsuffix=rsuffix)
             return x
 
         return (_transform_index(left, lrenamer),

pandas/core/reshape/merge.py

@@ -489,10 +489,6 @@ def __init__(self, left, right, how='inner', on=None,
 
         self.copy = copy
 
-        if suffixes[0] is None:
-            suffixes = ('', suffixes[1])
-        if suffixes[1] is None:
-            suffixes = (suffixes[0], '')
         self.suffixes = suffixes
 
         self.sort = sort

pandas/tests/reshape/merge/test_merge.py

@@ -1512,9 +1512,13 @@ def test_merge_series(on, left_on, right_on, left_index, right_index, nm):
 
 @pytest.mark.parametrize("col1, col2, suffixes, expected_cols", [
     (0, 0, ("", "_dup"), ["0", "0_dup"]),
-    (0, 0, (None, "_dup"), ["0", "0_dup"]),
+    (0, 0, (None, "_dup"), [0, "0_dup"]),
     (0, 0, ("_x", "_y"), ["0_x", "0_y"]),
-    ("a", 0, (None, "_y"), ["a", 0])
+    ("a", 0, (None, "_y"), ["a", 0]),
+    (0.0, 0.0, ("_x", None), ["0.0_x", 0.0]),
+    ("b", "b", (None, "_y"), ["b", "b_y"]),
+    ("a", "a", ("_x", None), ["a_x", "a"]),
+    ("a", "b", ("_x", None), ["a", "b"])
 ])
 def test_merge_suffix(col1, col2, suffixes, expected_cols):
     # issue: 24782