VB: add a vbench for groupby count

Author: cpcloud

vb_suite/groupby.py

@@ -119,6 +119,19 @@ def f():
                                setup, start_date=datetime(2011, 10, 1))
 
 #----------------------------------------------------------------------
+# count() speed
+
+setup = common_setup + """
+df = DataFrame({'key1': np.random.randint(0, 500, size=100000),
+                'key2': np.random.randint(0, 100, size=100000),
+                'value1' : np.random.randn(100000),
+                'value2' : np.random.randn(100000),
+                'value3' : np.random.randn(100000)})
+"""
+
+groupby_multi_count = Benchmark("df.groupby(['key1', 'key2']).count()",
+                                setup, start_date=datetime(2014, 5, 1))
+#----------------------------------------------------------------------
 # Series.value_counts
 
 setup = common_setup + """