Add Extend Array Function (#2771)

* Add Extend Array Function

* Fix Typo and restructure

* Restructure

* Doc string update

* Was expecting numpy arrays to be passed by reference but it is not so updating it

* Add test for the extend array function

tardis/transport/montecarlo/packet_trackers.py

@@ -16,6 +16,7 @@
     ("shell_id", int64[:]),
     ("interaction_type", int64[:]),
     ("num_interactions", int64),
+    ("extend_factor", int64),
 ]
 
 
@@ -47,6 +48,8 @@ class RPacketTracker(object):
             Type of interaction the rpacket undergoes
         num_interactions : int
             Internal counter for the interactions that a particular RPacket undergoes
+        extend_factor : int
+            The factor by which to extend the properties array when the size limit is reached
     """
 
     def __init__(self, length):
@@ -61,34 +64,27 @@ def __init__(self, length):
         self.shell_id = np.empty(self.length, dtype=np.int64)
         self.interaction_type = np.empty(self.length, dtype=np.int64)
         self.num_interactions = 0
+        self.extend_factor = 2
+
+    def extend_array(self, array, array_length):
+        temp_array = np.empty(
+            array_length * self.extend_factor, dtype=array.dtype
+        )
+        temp_array[:array_length] = array
+        return temp_array
 
     def track(self, r_packet):
         if self.num_interactions >= self.length:
-            temp_length = self.length * 2
-            temp_status = np.empty(temp_length, dtype=np.int64)
-            temp_r = np.empty(temp_length, dtype=np.float64)
-            temp_nu = np.empty(temp_length, dtype=np.float64)
-            temp_mu = np.empty(temp_length, dtype=np.float64)
-            temp_energy = np.empty(temp_length, dtype=np.float64)
-            temp_shell_id = np.empty(temp_length, dtype=np.int64)
-            temp_interaction_type = np.empty(temp_length, dtype=np.int64)
-
-            temp_status[: self.length] = self.status
-            temp_r[: self.length] = self.r
-            temp_nu[: self.length] = self.nu
-            temp_mu[: self.length] = self.mu
-            temp_energy[: self.length] = self.energy
-            temp_shell_id[: self.length] = self.shell_id
-            temp_interaction_type[: self.length] = self.interaction_type
-
-            self.status = temp_status
-            self.r = temp_r
-            self.nu = temp_nu
-            self.mu = temp_mu
-            self.energy = temp_energy
-            self.shell_id = temp_shell_id
-            self.interaction_type = temp_interaction_type
-            self.length = temp_length
+            self.status = self.extend_array(self.status, self.length)
+            self.r = self.extend_array(self.r, self.length)
+            self.nu = self.extend_array(self.nu, self.length)
+            self.mu = self.extend_array(self.mu, self.length)
+            self.energy = self.extend_array(self.energy, self.length)
+            self.shell_id = self.extend_array(self.shell_id, self.length)
+            self.interaction_type = self.extend_array(
+                self.interaction_type, self.length
+            )
+            self.length = self.length * self.extend_factor
 
         self.index = r_packet.index
         self.seed = r_packet.seed

tardis/transport/montecarlo/tests/test_rpacket_tracker.py

@@ -4,6 +4,7 @@
 
 from tardis.transport.montecarlo.r_packet import InteractionType
 from tardis.transport.montecarlo.packet_trackers import (
+    RPacketTracker,
     rpacket_trackers_to_dataframe,
 )
 
@@ -102,6 +103,17 @@ def nu_rpacket_tracker(rpacket_tracker):
     return nu
 
 
+def test_extend_array():
+    rpacket_tracker = RPacketTracker(10)
+    array = np.array([1, 2, 3, 4, 5], dtype=np.int64)
+
+    new_array = rpacket_tracker.extend_array(array, array.size)
+
+    assert new_array.size == array.size * rpacket_tracker.extend_factor
+    assert new_array.dtype == array.dtype
+    npt.assert_allclose(array, new_array[: array.size])
+
+
 @pytest.mark.parametrize(
     "expected,obtained",
     [