diff --git a/src/msspec/looper.py b/src/msspec/looper.py
index 0dbfdc4..4393022 100644
--- a/src/msspec/looper.py
+++ b/src/msspec/looper.py
@@ -17,8 +17,8 @@
 # along with this msspec.  If not, see <http://www.gnu.org/licenses/>.
 #
 # Source file  : src/msspec/looper.py
-# Last modified: Mon, 27 Sep 2021 17:49:48 +0200
-# Committed by : sylvain tricot <sylvain.tricot@univ-rennes1.fr>
+# Last modified: Wed, 26 Feb 2025 11:15:54 +0100
+# Committed by : Sylvain Tricot <sylvain.tricot@univ-rennes.fr>
 
 from collections import OrderedDict
 from functools import partial
@@ -92,9 +92,8 @@ class Sweep:
 
 
 class SweepRange:
-    def __init__(self, *sweeps, passindex=False):
+    def __init__(self, *sweeps):
         self.sweeps = sweeps
-        self.passindex = passindex
         self.index = 0
 
         # First check that sweeps that are linked to another on are all included
@@ -158,17 +157,15 @@ class SweepRange:
                     for s in [sweep,] + children:
                         key, value = s[idx]
                         row[key] = value
-                if self.passindex:
-                    row['sweep_index'] = i
+                row['sweep_index'] = i
             return row
         else:
             raise StopIteration
 
     @property
     def columns(self):
-        cols = [sweep.key for sweep in self.sweeps]
-        if self.passindex:
-            cols.append('sweep_index')
+        cols  = ['sweep_index']
+        cols += [sweep.key for sweep in self.sweeps]
         return cols
 
     @property
@@ -202,31 +199,27 @@ class Looper:
         logger.debug("Pipeline called with {}".format(x))
         return self.pipeline(**x)
 
-    def run(self, *sweeps, ncpu=1, passindex=False):
+    def run(self, *sweeps, ncpu=1, **kwargs):
         logger.info("Loop starts...")
         # prepare the list of inputs
-        sr = SweepRange(*sweeps, passindex=passindex)
+        sr = SweepRange(*sweeps)
         items = sr.items
 
         data = []
 
+        t0 = time.time()
+
         if ncpu == 1:
             # serial processing...
             logger.info("serial processing...")
-            t0 = time.time()
-
             for i, values in enumerate(items):
+                values.update(kwargs)
                 result = self._wrapper(values)
                 data.append(result)
-
-            t1 = time.time()
-            dt = t1 - t0
-            logger.info("Processed {:d} sets of inputs in {:.3f} seconds".format(
-                len(sr), dt))
-
         else:
             # Parallel processing...
             chunksize = 1 #int(nsets/ncpu)
+            [values.update(kwargs) for values in items]
             logger.info(("Parallel processing over {:d} cpu (chunksize={:d})..."
                          "").format(ncpu, chunksize))
             t0 = time.time()
@@ -236,21 +229,23 @@ class Looper:
             pool.close()
             pool.join()
 
-            t1 = time.time()
-            dt = t1 - t0
-            logger.info(("Processed {:d} sets of inputs in {:.3f} seconds"
-                         "").format(len(sr), dt))
+        t1 = time.time()
+        dt = t1 - t0
+        logger.info(("Processed {:d} sets of inputs in {:.3f} seconds"
+                        "").format(len(sr), dt))
 
         # Create the DataFrame
         dfdata = []
-        columns = sr.columns + ['output',]
+        columns = sr.columns + list(kwargs.keys()) + ['output',]
 
         for i in range(len(sr)):
             row = list(items[i].values())
             row.append(data[i])
             dfdata.append(row)
 
+
         df = pd.DataFrame(dfdata, columns=columns)
+        df = df.drop(columns=['sweep_index'])
 
         self.data = df
 
@@ -259,14 +254,14 @@ class Looper:
         # of corresponding dict of parameters {'keyA': [val0,...valn],
         # 'keyB': [val0,...valn], ...}
 
-        all_xy = []
-        for irow, row in df.iterrows():
-            all_xy.append(row.output[0])
-            all_xy.append(row.output[1])
-        parameters = df.to_dict()
-        parameters.pop('output')
+        # all_xy = []
+        # for irow, row in df.iterrows():
+            # all_xy.append(row.output[0])
+            # all_xy.append(row.output[1])
+        # parameters = df.to_dict()
+        # parameters.pop('output')
 
-        return all_xy, parameters
+        return self.data #all_xy, parameters
 
 
 
@@ -276,17 +271,16 @@ class Looper:
 if __name__ == "__main__":
     import numpy as np
     import time
+    import logging
+
+
+    logging.basicConfig(level=logging.DEBUG)
 
-    logger.setLevel(logging.DEBUG)
 
 
     def bar(**kwargs):
-        return 0
-
-    def post_process(data):
-        x = data.x.unique()
-        y = data.y.unique()
-
+        i = kwargs.get('sweep_index')
+        return np.linspace(0,i,10)
 
     theta = Sweep(key='theta', comments="The polar angle",
                   start=-70, stop=70, num=3,
@@ -314,7 +308,16 @@ if __name__ == "__main__":
 
     looper = Looper()
     looper.pipeline = bar
-    data = looper.run(emitter, emitter_plane, uij, theta, levels, ncpu=4,
-                      passindex=True)
+    other_kws = {'un':1, 'deux':2}
+    data = looper.run(emitter, emitter_plane, uij, theta, levels, ncpu=4, **other_kws)
+
+    # Print the dataframe
     print(data)
-    #print(data[data.emitter_plane.eq(0)].theta.unique())
+
+    # Accessing the parameters and ouput values for a given sweep (e.g the last one)
+    print(looper.data.iloc[-1])
+
+    # Post-process the output values. For example here, the output is a 1D-array,
+    # make the sum of sweeps with 'Sr' emitter
+    X = np.array([ x for x in data[data.emitter == 'Sr'].output]).sum(axis=0)
+    print(X)