Merge pull request #164 from mjerick25/dev-rename

Added implementation of CASTable.rename

Author: bkemper24

swat/cas/table.py

@@ -5959,8 +5959,47 @@ def drop_duplicates(self, casout, subset=[]):
 #   def reindex_like(self, *args, **kwargs):
 #       raise NotImplementedError
 
-#   def rename(self, *args, **kwargs):
-#       raise NotImplementedError
+    def rename(self, columns, errors='ignore', **kwargs):
+        '''
+        Rename columns of the CASTable.
+
+        Parameters
+        ----------
+        columns : dict or function
+            Transformations to apply to the columns of the CASTable.
+        errors : 'ignore' or 'raise', default 'ignore'
+            Given a dict with a key that does not match one of the columns
+            in the CASTable, this determines whether to ignore that key or
+            raise a KeyError.
+
+        Returns
+        -------
+        :class:`CASTable`
+        '''
+
+        # Columns is a dict:
+        alterTable = []
+        if isinstance(columns, dict):
+            # Convert Pandas-style dict to CAS-style list of dicts
+            for oldName, newName in columns.items():
+                if oldName in self.columns:
+                    alterTable.append({'name': oldName, 'rename': newName})
+                # If we encounter a key that doesn't exist as column
+                # and we are raising errors, we do that here
+                elif errors == 'raise':
+                    raise KeyError("Column is not found in CASTable: " + oldName)
+
+        # Columns is a function:
+        elif callable(columns):
+            # Iterate through all table columns and apply function
+            for col in self.columns:
+                alterTable.append({'name': col, 'rename': columns(col)})
+        else:
+            raise TypeError("Columns must be a dict or function")
+
+        # Use list of dicts to rename using alterTable action
+        self._retrieve('alterTable', columns=alterTable)
+        return self
 
     def reset_index(self, level=None, drop=False, inplace=False,
                     col_level=0, col_fill='', **kwargs):

swat/tests/cas/test_table.py

@@ -5174,6 +5174,50 @@ def test_partition_inputs(self):
         pcolinfo = pcolinfo.drop('ID', errors='ignore').drop('Label', errors='ignore')
         self.assertTablesEqual(colinfo[['Two', 'Model', 'One', 'MSRP']], pcolinfo)
 
+    def test_rename(self):
+        # Pull in CASTable and Pandas Dataframe
+        tbl = self.table
+        df = self.get_cars_df()
+
+        # Rename by name:
+        makeCol = tbl['Make']
+        self.assertTrue(any(col in 'Make' for col in list(tbl.columns)))
+        tbl.rename({'Make': 'Manufacturer'})
+        # We use inplace=True as that's what CASTable.rename is doing
+        df.rename(columns={'Make': 'Manufacturer'}, inplace=True)
+        # No column named "Make" and a column named "Manufacturer"
+        self.assertFalse(any(col in 'Make' for col in list(tbl.columns)))
+        self.assertTrue(any(col in 'Manufacturer' for col in list(tbl.columns)))
+        # Shouldn't be a "new" column, just 'Make' renamed
+        self.assertEqual(makeCol, tbl['Manufacturer'])
+        # Shoud be same as pandas
+        self.assertTablesEqual(tbl, df)
+
+        # Rename by function:
+        # Column Manufacturer -> Manufacturer_0
+        tbl.rename(lambda col: col + "_0")
+        df.rename(columns=lambda col: col + "_0", inplace=True)
+        for col in list(tbl.columns):
+            # Last two characters should be _0 for each col
+            self.assertEqual(col[-2:], "_0")
+        self.assertTablesEqual(tbl, df)
+
+        # Rename by name for col that doesn't exist
+        # errors='ignore'
+        originalCols = list(copy.deepcopy(tbl.columns))
+        # This column doesn't exist, so it'll just ignore it
+        tbl.rename({'nope': 'nuh uh'})
+        df.rename(columns={'nope': 'nuh uh'}, inplace=True)
+        self.assertFalse(any(col in 'nope' for col in list(tbl.columns)))
+        self.assertListEqual(originalCols, list(tbl.columns))
+        self.assertTablesEqual(tbl, df)
+
+        # Rename by name for col that doesn't exist
+        # errors='raise'
+        with self.assertRaises(KeyError):
+            # This column doesn't exist and errors='raise', it'll raise an exception
+            tbl.rename(tbl.rename({'nope': 'nuh uh'}, errors='raise'))
+
     def test_reset_index(self):
         tbl = self.table