Support for Dataset transposition. Unit-tested.

2 files changed, 42 insertions, 1 deletions

diff --git a/tablib/core.py b/tablib/core.py
index 1417000..23026a2 100644
--- a/tablib/core.py
+++ b/tablib/core.py
@@ -507,7 +507,35 @@ class Dataset(object):
 		_dset._data = [row for row in _dset._data if row.has_tag(tag)]
 		
 		return _dset
-	
+
+	def transpose(self):
+		"""Transpose a :class:`Dataset`, turning rows into columns and vice
+		versa, returning a new ``Dataset`` instance. The first row of the
+		original instance becomes the new header row."""
+
+		# Don't transpose if there is no data
+		if not self:
+			return
+
+		_dset = Dataset()
+		# The first element of the headers stays in the headers,
+		# it is our "hinge" on which we rotate the data
+		new_headers = [self.headers[0]] + self[self.headers[0]]
+		
+		_dset.headers = new_headers
+		for column in self.headers:
+
+			if column == self.headers[0]:
+				# It's in the headers, so skip it
+				continue
+
+			# Adding the column name as now they're a regular column
+			row_data = [column] + self[column]
+			row_data = Row(row_data)
+			_dset.append(row=row_data)
+
+		return _dset
+
 	def wipe(self):
 		"""Removes all content and headers from the :class:`Dataset` object."""
 		self._data = list()
diff --git a/test_tablib.py b/test_tablib.py
index 342fd45..55546b5 100755
--- a/test_tablib.py
+++ b/test_tablib.py
@@ -349,6 +349,19 @@ class TablibTestCase(unittest.TestCase):
 		self.assertEqual(tablib.detect(_json)[0], tablib.formats.json)
 		self.assertEqual(tablib.detect(_bunk)[0], None)
 
+	def test_transpose(self):
+		"""Transpose a dataset."""
+
+		transposed_founders = self.founders.transpose()
+		first_row = transposed_founders[0]
+		second_row = transposed_founders[1]
+		
+		self.assertEqual(transposed_founders.headers,
+				  ["first_name","John", "George", "Thomas"])
+		self.assertEqual(first_row,
+				   ("last_name","Adams", "Washington", "Jefferson"))
+		self.assertEqual(second_row,
+				   ("gpa",90, 67, 50))
 
 	def test_wipe(self):
 		"""Purge a dataset."""