Merge pull request #28 from cswegger/tablib

---

This patch provides simple column-based sorting to tablib. A (passing) unit-test is also included.

2 files changed, 35 insertions, 0 deletions

diff --git a/tablib/core.py b/tablib/core.py
index c7e9dd5..5727a69 100644
--- a/tablib/core.py
+++ b/tablib/core.py
@@ -10,6 +10,7 @@
 """
 
 from copy import copy
+from operator import itemgetter
 
 from tablib import formats
 
@@ -528,6 +529,25 @@ class Dataset(object):
 
 		return _dset
 
+	def sort(self, col, reverse=False):
+
+		"""Sort a :class:`Dataset` by a specific column. The order can be
+		reversed by setting ``reverse`` to ``True``. Requires headers to be
+		set. Returns a new :class:`Dataset` instance where columns have been
+		sorted."""
+
+		if not self.headers:
+			raise HeadersNeeded
+
+		_sorted = sorted(self.dict, key=itemgetter(col), reverse=reverse)
+		_dset = Dataset(headers=self.headers)
+
+		for item in _sorted:
+			row = [item[key] for key in self.headers]
+			_dset.append(row=row)
+
+		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
diff --git a/test_tablib.py b/test_tablib.py
index 2d1f6b4..15630f2 100755
--- a/test_tablib.py
+++ b/test_tablib.py
@@ -425,7 +425,22 @@ class TablibTestCase(unittest.TestCase):
 		self.assertEqual(column_stacked[0],
 				   ("John", "Adams", 90, "John", "Adams", 90))
 
+	def test_sorting(self):
 
+		"""Sort columns."""
+
+		sorted_data = self.founders.sort(col="first_name")
+
+		first_row = sorted_data[0]
+		second_row = sorted_data[2]
+		third_row = sorted_data[1]
+		expected_first = self.founders[1]
+		expected_second = self.founders[2]
+		expected_third = self.founders[0]
+
+		self.assertEqual(first_row, expected_first)
+		self.assertEqual(second_row, expected_second)
+		self.assertEqual(third_row, expected_third)
 
 	def test_wipe(self):
 		"""Purge a dataset."""