Add metadata file support to csv trace

pydtn/__init__.py

@@ -35,6 +35,7 @@ __author__ = 'Jarrod Pas <j.pas@usask.ca>'
 
 from collections import ChainMap, defaultdict, namedtuple, OrderedDict
 import csv
+import json
 from itertools import count
 from random import Random
 from time import time
@@ -176,6 +177,10 @@ class Network:
         stats['broadcasts'] = sum(nodes['broadcasts'])
         stats['delivery-cost'] = stats['broadcasts'] / stats['recieved']
 
+        for stat, values in packets.items():
+            if stat.startswith('hops'):
+                stats[stat] = sum(values)
+
         stats.update(self._stats)
         return stats
 
@@ -569,39 +574,49 @@ class CSVTrace(Trace):
 
     The first row is used as headers.
 
-    The second row is the following information about the trace:
-    [ int(duration), int(node_count), ignored, ignored ]
-
     The csv uses the following columns:
     [ int(time), int(node_a), int(node_b), int(join) ]
     time -- simulation time that the contact even happens
     node_{a,b} -- nodes involved in contact
     join -- whether the contact is going up (1) or going down (0)
+
+    Optionally accepts a metadata file so it does not have to read and store
+    the entire trace at once the beginning.
     """
 
-    def __init__(self, path):
+    def __init__(self, path, metadata=None):
         """Create a csv trace generator."""
-        with open(path) as csv_file:
-            csv_file = csv.reader(csv_file)
-            # skip header
-            next(csv_file)
-            # get node count from first row of csv. it is additional stats
-            # about the trace
-            # duration, placeholder, placehold, node_count
-            nodes = int(next(csv_file)[1])
+        self.path = path
+        self._contacts = None
+
+        if metadata is None:
+            nodes = len(list(self.contacts))
+        else:
+            with open(metadata) as metadata_file:
+                nodes = json.load(metadata_file)['nodes']
 
         super().__init__(nodes)
-        self.path = path
 
-    def __iter__(self):
-        """Yield contacts from csv file."""
+    @property
+    def contacts(self):
+        if self._contacts is not None:
+            yield from self._contacts
+
+        contacts = []
         with open(self.path) as csv_file:
             csv_file = csv.reader(csv_file)
-            # skip header and first row
-            next(csv_file)
+            # skip header
             next(csv_file)
             for row in csv_file:
-                yield self.create_contact(*map(int, row))
+                contact = self.create_contact(*map(int, row))
+                contacts.append(contact)
+                yield contact
+
+        self._contacts = contacts
+
+    def __iter__(self):
+        """Yield contacts from csv file."""
+        yield from self.contacts
 
 
 class RandomTrace(Trace):