add ASV

Author: smithto1

asv_bench/benchmarks/groupby.py

@@ -369,6 +369,21 @@ def time_category_size(self):
         self.draws.groupby(self.cats).size()
 
 
+class Shift:
+    def setup(self):
+        N = 18
+        self.df = DataFrame({
+            'g' : ['a', 'b'] * 9, 
+            'v' : list(range(N))
+            })
+    
+    def time_defaults(self):
+        self.df.groupby('g').shift()
+    
+    def time_fill_value(self):
+        self.df.groupby('g').shift(fill_value=99)
+
+
 class FillNA:
     def setup(self):
         N = 100