diff --git a/Inst_eddies/Analysis/distribution_function.py b/Inst_eddies/Analysis/distribution_function.py
index 76a7a6cd37a716585ddfac24ef95bb92a24885d2..118aed97089c5129d7fc932ad3ea19b51322b750 100755
--- a/Inst_eddies/Analysis/distribution_function.py
+++ b/Inst_eddies/Analysis/distribution_function.py
@@ -8,7 +8,7 @@ import numpy as np
 import jumble_matplotlib
 
 
-def read(SHPC):
+def read(SHPC, i_slice, orientation):
     """Read the three dbf files in dirname and return speed, radius and
     amplitude of outermost contour, radius and amplitude of maximum
     speed contour, as Numpy arrays.
@@ -16,9 +16,9 @@ def read(SHPC):
     Select valid speed values.
 
     """
-    extremum = SHPC.get_reader(0, "Anticyclones", "extremum")
-    outerm_cont = SHPC.get_reader(0, "Anticyclones", "outermost_contour")
-    max_speed_cont = SHPC.get_reader(0, "Anticyclones", "max_speed_contour")
+    extremum = SHPC.get_reader(i_slice, orientation, "extremum")
+    outerm_cont = SHPC.get_reader(i_slice, orientation, "outermost_contour")
+    max_speed_cont = SHPC.get_reader(i_slice, orientation, "max_speed_contour")
     speed = []
     rad_outer = []
     rad_speed = []
@@ -132,10 +132,12 @@ if __name__ == "__main__":
 
     parser = argparse.ArgumentParser()
     parser.add_argument("SHPC", help="directory containing SHPC")
+    parser.add_argument("i_slice", help="slice index", type=int)
+    parser.add_argument("orientation", choices=["Anticyclones", "Cyclones"])
     parser.add_argument("--save", action="store_true")
     args = parser.parse_args()
     SHPC = util_eddies.SHPC_class(args.SHPC)
-    d = read(SHPC)
+    d = read(SHPC, args.i_slice, args.orientation)
     fig_list = plot_all([d])
 
     if args.save:
diff --git a/Inst_eddies/Analysis/tests.json b/Inst_eddies/Analysis/tests.json
index ea06319ec1d6c5f0790e72691331f32e446b348d..b7ed91799029015ded41b55a37bc43eb7c2031f3 100644
--- a/Inst_eddies/Analysis/tests.json
+++ b/Inst_eddies/Analysis/tests.json
@@ -131,6 +131,8 @@
     "command": [
       "$src_dir/Inst_eddies/Analysis/distribution_function.py",
       "$tests_old_dir/Region_5_15_days/SHPC",
+      "0",
+      "Anticyclones",
       "--save"
     ]
   }