Update NA repr

Closes pandas-dev#30415

Author: TomAugspurger

pandas/_libs/missing.pyx

@@ -354,10 +354,7 @@ class NAType(C_NAType):
         return NAType._instance
 
     def __repr__(self) -> str:
-        return "NA"
-
-    def __str__(self) -> str:
-        return "NA"
+        return "<NA>"
 
     def __bool__(self):
         raise TypeError("boolean value of NA is ambiguous")

pandas/io/formats/format.py

@@ -1230,7 +1230,7 @@ def _format(x):
                     if x is None:
                         return "None"
                     elif x is NA:
-                        return "NA"
+                        return formatter(x)
                     elif x is NaT or np.isnat(x):
                         return "NaT"
                 except (TypeError, ValueError):

pandas/tests/arrays/test_boolean.py

@@ -335,7 +335,7 @@ def test_astype():
     tm.assert_numpy_array_equal(result, expected)
 
     result = arr.astype("str")
-    expected = np.array(["True", "False", "NA"], dtype="object")
+    expected = np.array(["True", "False", "<NA>"], dtype="object")
     tm.assert_numpy_array_equal(result, expected)
 
     # no missing values

pandas/tests/arrays/test_integer.py

@@ -90,17 +90,17 @@ def test_repr_dtype(dtype, expected):
 
 def test_repr_array():
     result = repr(integer_array([1, None, 3]))
-    expected = "<IntegerArray>\n[1, NA, 3]\nLength: 3, dtype: Int64"
+    expected = "<IntegerArray>\n[1, <NA>, 3]\nLength: 3, dtype: Int64"
     assert result == expected
 
 
 def test_repr_array_long():
     data = integer_array([1, 2, None] * 1000)
     expected = (
         "<IntegerArray>\n"
-        "[ 1,  2, NA,  1,  2, NA,  1,  2, NA,  1,\n"
+        "[   1,    2, <NA>,    1,    2, <NA>,    1,    2, <NA>,    1,\n"
         " ...\n"
-        " NA,  1,  2, NA,  1,  2, NA,  1,  2, NA]\n"
+        " <NA>,    1,    2, <NA>,    1,    2, <NA>,    1,    2, <NA>]\n"
         "Length: 3000, dtype: Int64"
     )
     result = repr(data)
@@ -673,7 +673,7 @@ def test_to_numpy_na_raises(self, dtype):
 
     def test_astype_str(self):
         a = pd.array([1, 2, None], dtype="Int64")
-        expected = np.array(["1", "2", "NA"], dtype=object)
+        expected = np.array(["1", "2", "<NA>"], dtype=object)
 
         tm.assert_numpy_array_equal(a.astype(str), expected)
         tm.assert_numpy_array_equal(a.astype("str"), expected)
@@ -683,7 +683,7 @@ def test_frame_repr(data_missing):
 
     df = pd.DataFrame({"A": data_missing})
     result = repr(df)
-    expected = "    A\n0  NA\n1   1"
+    expected = "      A\n0  <NA>\n1     1"
     assert result == expected