[Fix] Bunch & WakePotential

Update gitignore

.gitignore

@@ -2,3 +2,4 @@
 *.ipynb_checkpoints*
 test_*.py
 *.hdf5
+*.pyc

mbtrack2/tracking/particles.py

@@ -129,12 +129,12 @@ class Bunch:
         self._mp_number = int(mp_number)
 
         self.particles = {
-            "x": np.empty(self.mp_number, dtype=np.float64),
-            "xp": np.empty(self.mp_number, dtype=np.float64),
-            "y": np.empty(self.mp_number, dtype=np.float64),
-            "yp": np.empty(self.mp_number, dtype=np.float64),
-            "tau": np.empty(self.mp_number, dtype=np.float64),
-            "delta": np.empty(self.mp_number, dtype=np.float64),
+            "x": np.zeros(self.mp_number, dtype=np.float64),
+            "xp": np.zeros(self.mp_number, dtype=np.float64),
+            "y": np.zeros(self.mp_number, dtype=np.float64),
+            "yp": np.zeros(self.mp_number, dtype=np.float64),
+            "tau": np.zeros(self.mp_number, dtype=np.float64),
+            "delta": np.zeros(self.mp_number, dtype=np.float64),
         }
         self.track_alive = track_alive
         self.alive = np.ones((self.mp_number, ), dtype=bool)
@@ -165,11 +165,13 @@ class Bunch:
 
     def __iter__(self):
         """Iterate over labels"""
-        return self.dtype.names.__iter__()
+        return self.particles.keys().__iter__()
 
     def __repr__(self):
         """Return representation of alive particles"""
-        return f'Bunch with macro-particles: \n {pd.DataFrame(self[:])!r}'
+        rep = pd.DataFrame(np.array([self[l] for l in self.__iter__()]).T,
+                           columns=list(self.__iter__()))
+        return f'Bunch with macro-particles: \n {rep!r}'
 
     @property
     def mp_number(self):

mbtrack2/tracking/wakepotential.py

@@ -231,7 +231,7 @@ class WakePotential(Element):
                              dtau0)
             W0 = np.insert(W0, 0, np.zeros(n))
             n_to_add = len(tau0) - len(W0)
-            W0 = np.pad(W0, (n, n_to_add),
+            W0 = np.pad(W0, (0, n_to_add),
                         mode="constant",
                         constant_values=(0, 0))