Added a row_names arg to Table.merge. Closes wireservice#403.

CHANGELOG.rst

@@ -1,6 +1,7 @@
 1.1.1
 -----
 
+* :meth:`.Table.merge` now accepts a ``row_names`` argument. (#403)
 * :class:`.Formula` now automatically casts computed values to specified data type unless ``invalidate`` is set to ``False``. (#398)
 * Added Neil Bedi to AUTHORS.
 * :meth:`.Table.rename` is implemented. (#389)

agate/table.py

@@ -41,7 +41,6 @@
 from agate.aggregations import Min, Max
 from agate.columns import Column
 from agate.data_types import TypeTester, DataType, Text, Number
-from agate.computations import Computation
 from agate.mapped_sequence import MappedSequence
 from agate.preview import print_table, print_bars
 from agate.rows import Row
@@ -90,7 +89,9 @@ class Table(utils.Patchable):
         optional. If specified it may be 1) the name of a single column that
         contains a unique identifier for each row, 2) a key function that takes
         a :class:`.Row` and returns a unique identifier or 3) a sequence of
-        unique identifiers of the same length as the sequence of rows.
+        unique identifiers of the same length as the sequence of rows. The
+        uniqueness of resulting identifiers is not validated, so be certain
+        the values you provide are truly unique.
     :param _is_fork:
         Used internally to skip certain validation steps when data
         is propagated from an existing table. When :code:`True`, rows are
@@ -847,15 +848,20 @@ def join(self, right_table, left_key, right_key=None, inner=False):
         return self._fork(rows, column_names, column_types, row_names=row_names)
 
     @classmethod
-    def merge(cls, tables):
+    def merge(cls, tables, row_names=None):
         """
         Merge an array of tables with identical columns into a single table.
         Each table must have exactly the same column types. Their column names
         need not be identical. The first table's column names will be the ones
         which are used.
 
+        Row names will be lost, but new row names can be specified with the
+        `row_names` argument.
+
         :param tables:
             An sequence of :class:`Table` instances.
+        :param row_names:
+            See :class:`Table` for the usage of this parameter.
         :returns:
             A new :class:`Table`.
         """
@@ -875,7 +881,7 @@ def merge(cls, tables):
                 for row in table.rows:
                     rows.append(Row(row.values(), column_names))
 
-        return Table(rows, column_names, column_types, row_names=tables[0].row_names, _is_fork=True)
+        return Table(rows, column_names, column_types, row_names=row_names, _is_fork=True)
 
     @allow_tableset_proxy
     def group_by(self, key, key_name=None, key_type=None):

tests/test_computations.py

@@ -62,10 +62,6 @@ def test_formula_no_validate(self):
             ('test', Formula(self.number_type, lambda r: r['one'], validate=False))
         ])
 
-        self.assertIsNot(new_table, self.table)
-        self.assertEqual(len(new_table.rows), 4)
-        self.assertEqual(len(new_table.columns), 5)
-
         # Now everything is screwed up
         self.assertSequenceEqual(new_table.rows[0], ('a', Decimal('2'), Decimal('3'), Decimal('4'), 'a'))
         self.assertEqual(new_table.columns['test'][0], 'a')

tests/test_table.py

@@ -1493,10 +1493,17 @@ def test_merge_different_types(self):
 
     def test_merge_with_row_names(self):
         table_a = Table(self.rows, self.column_names, self.column_types, row_names='three')
-        table_b = Table(self.rows, self.column_names, self.column_types)
-        table_c = Table.merge([table_a, table_b])
 
-        self.assertRowNames(table_c, table_a.row_names)
+        b_rows = (
+            (1, 4, 'd'),
+            (2, 3, 'e'),
+            (None, 2, 'f')
+        )
+
+        table_b = Table(b_rows, self.column_names, self.column_types, row_names='three')
+        table_c = Table.merge([table_a, table_b], row_names='three')
+
+        self.assertRowNames(table_c, ['a', 'b', 'c', 'd', 'e', 'f'])
 
 class TestData(AgateTestCase):
     def setUp(self):