FIX-modin-project#3764: Fix KeyError from for out of range index

docs/release_notes/release_notes-0.16.0.rst

@@ -46,6 +46,7 @@ Key Features and Updates
   * FIX-#3983: FIX-#4107: Materialize 'rowid' columns when selecting rows by position (#4834)
   * FIX-#4845: Fix KeyError from `__getitem_bool` for single row dataframes (#4845)
   * FIX-#4734: Handle Series.apply when return type is a DataFrame (#4830)
+  * FIX-#3764: Fix KeyError from `__setitem__` for out of range index (#3764)
 * Performance enhancements
   * PERF-#4182: Add cell-wise execution for binary ops, fix bin ops for empty dataframes (#4391)
   * PERF-#4288: Improve perf of `groupby.mean` for narrow data (#4591)

modin/pandas/indexing.py

@@ -766,9 +766,8 @@ def _loc(df):
             return
         row_loc, col_loc, _ = self._parse_row_and_column_locators(key)
         if isinstance(row_loc, int) and row_loc not in self.qc.index:
-            # if row_loc not in self.qc.index:
             index = self.qc.index.insert(len(self.qc.index), row_loc)
-            self.qc = self.qc.reindex(labels=index, axis=0)
+            self.qc = self.qc.reindex(labels=index, axis=0, fill_value=0)
             self.df._update_inplace(new_query_compiler=self.qc)
         if isinstance(col_loc, int) and col_loc not in self.qc.columns:
             new_col = pandas.Series(index=self.df.index)

modin/pandas/test/dataframe/test_indexing.py

@@ -2117,3 +2117,14 @@ def test__getitem_bool_single_row_dataframe():
     # This test case comes from
     # https://github.com/modin-project/modin/issues/4845
     eval_general(pd, pandas, lambda lib: lib.DataFrame([1])[lib.Series([True])])
+
+
+def test_setitem_index_out_of_range():
+    # This test case comes from
+    # https://github.com/modin-project/modin/issues/3764
+    def set_new_row(lib):
+        df = lib.DataFrame([[1, 2], [3, 4]])
+        df.loc[2] = df.loc[1]
+        return df
+
+    eval_general(pd, pandas, set_new_row)