Improve sorting in dataframe editor

spyderlib/widgets/variableexplorer/dataframeeditor.py

@@ -269,12 +269,20 @@ def sort(self, column, order=Qt.AscendingOrder):
                                      "relation is defined for complex numbers")
                 return False
         try:
+            ascending = order == Qt.AscendingOrder
             if column > 0:
-                self.df.sort(columns=self.df.columns[column-1],
-                             ascending=order, inplace=True)
+                try:
+                    self.df.sort_values(by=self.df.columns[column-1],
+                                        ascending=ascending, inplace=True,
+                                        kind='mergesort')
+                except AttributeError:
+                    # for pandas version < 0.17
+                    self.df.sort(columns=self.df.columns[column-1],
+                                 ascending=ascending, inplace=True,
+                                 kind='mergesort')
                 self.update_df_index()
             else:
-                self.df.sort_index(inplace=True, ascending=order)
+                self.df.sort_index(inplace=True, ascending=ascending)
                 self.update_df_index()
         except TypeError as e:
             QMessageBox.critical(self.dialog, "Error",

spyderlib/widgets/variableexplorer/tests/test_dataframeeditor.py

@@ -0,0 +1,57 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright © 2009- The Spyder Development Team
+# Licensed under the terms of the MIT License
+
+"""
+Tests for dataframeeditor.py
+"""
+
+# Third party imports
+from pandas import DataFrame
+import pytest
+
+# Local imports
+from spyderlib.widgets.variableexplorer.dataframeeditor import DataFrameModel
+
+
+# --- Tests
+# -----------------------------------------------------------------------------
+def test_dataframemodel_basic():
+    df = DataFrame({'colA': [1, 3], 'colB': ['c', 'a']})
+    dfm = DataFrameModel(df)
+    assert dfm.rowCount() == 2
+    assert dfm.columnCount() == 3
+    assert dfm.data(dfm.createIndex(0, 0)) == '0'
+    assert dfm.data(dfm.createIndex(0, 1)) == '1'
+    assert dfm.data(dfm.createIndex(0, 2)) == 'c'
+    assert dfm.data(dfm.createIndex(1, 0)) == '1'
+    assert dfm.data(dfm.createIndex(1, 1)) == '3'
+    assert dfm.data(dfm.createIndex(1, 2)) == 'a'
+
+def test_dataframemodel_sort():
+    df = DataFrame({'colA': [1, 3], 'colB': ['c', 'a']})
+    dfm = DataFrameModel(df)
+    dfm.sort(2)
+    assert dfm.data(dfm.createIndex(0, 0)) == '1'
+    assert dfm.data(dfm.createIndex(0, 1)) == '3'
+    assert dfm.data(dfm.createIndex(0, 2)) == 'a'
+    assert dfm.data(dfm.createIndex(1, 0)) == '0'
+    assert dfm.data(dfm.createIndex(1, 1)) == '1'
+    assert dfm.data(dfm.createIndex(1, 2)) == 'c'
+
+def test_dataframemodel_sort_is_stable():   # cf. issue 3010
+    df = DataFrame([[2,14], [2,13], [2,16], [1,3], [2,9], [1,15], [1,17],
+                    [2,2], [2,10], [1,6], [2,5], [2,8], [1,11], [1,1],
+                    [1,12], [1,4], [2,7]])
+    dfm = DataFrameModel(df)
+    dfm.sort(2)
+    dfm.sort(1)
+    col2 = [dfm.data(dfm.createIndex(i, 2)) for i in range(len(df))]
+    assert col2 == [str(x) for x in [1, 3, 4, 6, 11, 12, 15, 17,
+                                     2, 5, 7, 8, 9, 10, 13, 14, 16]]
+
+
+if __name__ == "__main__":
+    pytest.main()
+