diff --git a/dask_test.py b/dask_test.py
index a38abc6..b92c8f0 100644
--- a/dask_test.py
+++ b/dask_test.py
@@ -52,10 +52,10 @@ try:
         print(dp.count().compute())
 
     with Timing("mean latitude"):
-        print(dp.map_partitions(lambda p: p.groupby(p.index).latitude.mean()).compute())
+        print(dp.groupby(dp.index).latitude.mean().compute())
 
     with Timing("mean longitude"):
-        print(dp.map_partitions(lambda p: p.groupby(p.index).longitude.mean()).compute())
+        print(dp.groupby(dp.index).longitude.mean().compute())
 
 finally:
     ########## FIN #######################
diff --git a/run_cluster.py b/run_cluster.py
index 1350e8c..815cf1f 100644
--- a/run_cluster.py
+++ b/run_cluster.py
@@ -1,3 +1,4 @@
+import sys
 import minerva
 from   minerva.pier     import Pier
 
@@ -32,7 +33,7 @@ pier    = m.pier(subnet_id = "subnet-05eb26d8649a093e1", # project-subnet-public
                  key_pair  = ("Ari-Brown-HAY", "~/.ssh/Ari-Brown-HAY.pem"),
                  iam       = "Minerva")
 
-cluster = pier.cluster(scheduler, worker, num_workers=5)
+cluster = pier.cluster(scheduler, worker, num_workers=sys.argv[1])
 cluster.start()
 print(cluster.public_location)