BUG: rank with object dtype and small values #62036

new change

new change

Author: Tejaswini V

pandas/_libs/algos.pyx

@@ -71,14 +71,6 @@ tiebreakers = {
     "dense": TIEBREAK_DENSE,
 }
 
-
-cdef bint are_diff(object left, object right):
-    try:
-        return fabs(left - right) > FP_ERR
-    except TypeError:
-        return left != right
-
-
 class Infinity:
     """
     Provide a positive Infinity comparison method for ranking.
@@ -1135,11 +1127,7 @@ cdef void rank_sorted_1d(
             dups += 1
             sum_ranks += i - grp_start + 1
 
-            if numeric_object_t is object:
-                next_val_diff = at_end or are_diff(masked_vals[sort_indexer[i]],
-                                                   masked_vals[sort_indexer[i+1]])
-            else:
-                next_val_diff = at_end or (masked_vals[sort_indexer[i]]
+            next_val_diff = at_end or (masked_vals[sort_indexer[i]]
                                            != masked_vals[sort_indexer[i+1]])
 
             # We'll need this check later anyway to determine group size, so just

pandas/tests/test_algos.py

@@ -31,6 +31,7 @@
     IntervalIndex,
     MultiIndex,
     NaT,
+    NA,
     Period,
     PeriodIndex,
     Series,
@@ -1809,6 +1810,13 @@ def test_uint64_overflow(self, dtype):
         s = Series([1, 2**63], dtype=dtype)
         tm.assert_numpy_array_equal(algos.rank(s), exp)
 
+    @pytest.mark.parametrize("method", ["average", "min", "max"])
+    def test_object_dtype(self, method):
+        exp = np.array([4.0, 1.0, 3.0, np.nan, 2.0], dtype=np.float64)
+        s = Series([5.4954145e29, -9.791984e-21, 9.3715776e-26, pd.NA, 1.8790257e-28], dtype="Float64")
+        s = s.astype(object)
+        tm.assert_numpy_array_equal(algos.rank(s, method=method), exp)
+
     def test_too_many_ndims(self):
         arr = np.array([[[1, 2, 3], [4, 5, 6], [7, 8, 9]]])
         msg = "Array with ndim > 2 are not supported"