Update frame.py

Author: stevenae

pandas/core/frame.py

@@ -5165,14 +5165,22 @@ def lookup(self, row_labels, col_labels) -> np.ndarray:
             # GH#33041
             raise ValueError("DataFrame.lookup requires unique index and columns")
 
-        values = self.to_numpy()
+        # values = self.to_numpy()
         ridx = self.index.get_indexer(row_labels)
         cidx = self.columns.get_indexer(col_labels)
         if (ridx == -1).any():
             raise KeyError("One or more row labels was not found")
         if (cidx == -1).any():
             raise KeyError("One or more column labels was not found")
-        flat_index = ridx * len(self.columns) + cidx
+
+        sub = self.take(np.unique(cidx), axis=1)
+        if sub._is_mixed_type:
+            sub = sub.take(np.unique(ridx), axis=0)
+            ridx = sub.index.get_indexer(row_labels)
+        values = sub.to_numpy()
+        cidx = sub.columns.get_indexer(col_labels)
+        flat_index = ridx * len(sub.columns) + cidx
+
         result = values.flat[flat_index]
 
         if is_object_dtype(result):