Add default behavior of no grouping if no group specs are given

Also add tests for this behavior

pandas_sequence/sequence.py

@@ -243,8 +243,11 @@ def sequence_df(df, lags, group_specs):
     for col_name in integer_columns.index:
         temp_df.loc[:,col_name] = temp_df.loc[:,col_name].astype(pd.Int64Dtype())
 
-    # Produce Groupby
-    # Groupby
+    if (by is None) and (level is None):
+        # No need to group the DataFrame here.
+        temp_gbydf = temp_df
+    else:
+        # Produce Groupby DataFrame
         temp_gbydf = temp_df.groupby(by=by, level=level, axis=0)
 
     dfs = []

tests/test_functionality.py

@@ -603,3 +603,145 @@ def test_large_1_6():
     target_df.columns = pd.MultiIndex.from_tuples(list(target_df.columns))
 
     pd.testing.assert_frame_equal(sequenced_df, target_df)
+
+def test_nogrouping_1():
+    # Build test DataFrame
+    df = pd.DataFrame(
+        [['2020-01-01', 0.2],
+         ['2020-01-02', -0.1],
+         ['2020-01-04', 0.345],
+         ['2020-01-05', 0.55],
+         ['2020-01-06', 1.2],
+         ['2020-01-07', -2.5],
+         ['2020-01-08', 3.7],
+         ['2020-01-10', 3.5],
+         ['2020-01-11', 0.3],
+         ['2020-01-13', -1.],
+         ['2020-01-01', -2.1],
+         ['2020-01-02', 1.1],
+         ['2020-01-03', 1.123],
+         ['2020-01-04', 5.3],
+         ['2020-01-05', 5.55]],
+        columns=['Date', 'Value'],
+    )
+    df['Date'] = pd.to_datetime(df['Date'])
+    df = df.set_index('Date')
+
+    sequenced_df = pds.sequence_df(df, [-1, 0], [])
+
+    target_df = pd.DataFrame(
+         [['2020-01-02', 0.2, -0.1],
+          ['2020-01-04', -0.1, 0.345],
+          ['2020-01-05', 0.345, 0.55],
+          ['2020-01-06', 0.55, 1.2],
+          ['2020-01-07', 1.2, -2.5],
+          ['2020-01-08', -2.5, 3.7],
+          ['2020-01-10', 3.7, 3.5],
+          ['2020-01-11', 3.5, 0.3],
+          ['2020-01-13', 0.3, -1.],
+          ['2020-01-01', -1., -2.1],
+          ['2020-01-02', -2.1, 1.1],
+          ['2020-01-03', 1.1, 1.123],
+          ['2020-01-04', 1.123, 5.3],
+          ['2020-01-05', 5.3, 5.55]],
+        columns=['Date', ('Value', -1), ('Value', 0)],
+    )
+    target_df['Date'] = pd.to_datetime(target_df['Date'])
+    target_df = target_df.set_index('Date')
+    target_df.columns = pd.MultiIndex.from_tuples(list(target_df.columns))
+
+    pd.testing.assert_frame_equal(sequenced_df, target_df)
+
+def test_nogrouping_2():
+    # Build test DataFrame
+    df = pd.DataFrame(
+        [['2020-01-01 00:00:00', 0.2],
+         ['2020-01-01 01:00:00', -0.1],
+         ['2020-01-01 02:00:00', 0.345],
+         ['2020-01-01 03:00:00', 0.55],
+         ['2020-01-01 04:00:00', 1.2],
+         ['2020-01-01 05:00:00', -2.5],
+         ['2020-01-01 06:00:00', 3.7],
+         ['2020-01-01 07:00:00', 3.5],
+         ['2020-01-01 08:00:00', 0.3],
+         ['2020-01-01 09:00:00', -1.],
+         ['2020-01-01 10:00:00', -2.1],
+         ['2020-01-01 11:00:00', 1.1],
+         ['2020-01-01 12:00:00', 1.123],
+         ['2020-01-01 13:00:00', 5.3],
+         ['2020-01-01 14:00:00', 5.55]],
+        columns=['Date', 'Value'],
+    )
+    df['Date'] = pd.to_datetime(df['Date'])
+    df = df.set_index('Date')
+
+    sequenced_df = pds.sequence_df(df, [-1, 0], [])
+
+    target_df = pd.DataFrame(
+         [['2020-01-01 01:00:00', 0.2, -0.1],
+          ['2020-01-01 02:00:00', -0.1, 0.345],
+          ['2020-01-01 03:00:00', 0.345, 0.55],
+          ['2020-01-01 04:00:00', 0.55, 1.2],
+          ['2020-01-01 05:00:00', 1.2, -2.5],
+          ['2020-01-01 06:00:00', -2.5, 3.7],
+          ['2020-01-01 07:00:00', 3.7, 3.5],
+          ['2020-01-01 08:00:00', 3.5, 0.3],
+          ['2020-01-01 09:00:00', 0.3, -1.],
+          ['2020-01-01 10:00:00', -1., -2.1],
+          ['2020-01-01 11:00:00', -2.1, 1.1],
+          ['2020-01-01 12:00:00', 1.1, 1.123],
+          ['2020-01-01 13:00:00', 1.123, 5.3],
+          ['2020-01-01 14:00:00', 5.3, 5.55]],
+        columns=['Date', ('Value', -1), ('Value', 0)],
+    )
+    target_df['Date'] = pd.to_datetime(target_df['Date'])
+    target_df = target_df.set_index('Date')
+    target_df.columns = pd.MultiIndex.from_tuples(list(target_df.columns))
+
+    pd.testing.assert_frame_equal(sequenced_df, target_df)
+
+def test_nogrouping_3():
+    # Build test DataFrame
+    df = pd.DataFrame(
+        [['A', 0.2],
+         ['A', -0.1],
+         ['A', 0.345],
+         ['A', 0.55],
+         ['B', 1.2],
+         ['B', -2.5],
+         ['B', 3.7],
+         ['B', 3.5],
+         ['B', 0.3],
+         ['C', -1.],
+         ['D', -2.1],
+         ['E', 1.1],
+         ['A', 1.123],
+         ['A', 5.3],
+         ['A', 5.55]],
+        columns=['Group', 'Value'],
+    )
+    df = df.set_index('Group')
+
+    sequenced_df = pds.sequence_df(df, [-1, 0], [])
+
+    target_df = pd.DataFrame(
+         [['A', 0.2, -0.1],
+          ['A', -0.1, 0.345],
+          ['A', 0.345, 0.55],
+          ['B', 0.55, 1.2],
+          ['B', 1.2, -2.5],
+          ['B', -2.5, 3.7],
+          ['B', 3.7, 3.5],
+          ['B', 3.5, 0.3],
+          ['C', 0.3, -1.],
+          ['D', -1., -2.1],
+          ['E', -2.1, 1.1],
+          ['A', 1.1, 1.123],
+          ['A', 1.123, 5.3],
+          ['A', 5.3, 5.55]],
+        columns=['Group', ('Value', -1), ('Value', 0)],
+    )
+    target_df = target_df.set_index('Group')
+    target_df.columns = pd.MultiIndex.from_tuples(list(target_df.columns))
+
+    pd.testing.assert_frame_equal(sequenced_df, target_df)