Generalize input of `extract_component.py`

Generalize `extract_component.py` so it can also read a graph in
graph-tool or graphml format.

Trajectories/extract_component.py

@@ -3,10 +3,20 @@
 import graph_tool
 import csv
 from graph_tool import topology
+import pathlib
+import sys
+
+input_suffix = pathlib.Path(sys.argv[1]).suffix
+
+if input_suffix == ".csv":
+    g = graph_tool.load_graph_from_csv(sys.argv[1], directed = True,
+                                       csv_options = {'delimiter': ' ',
+                                                      'skipinitialspace': True})
+elif input_suffix in {".gt", ".graphml"}:
+    g = graph_tool.load_graph(sys.argv[1])
+else:
+    sys.exit('Bad input file suffix.')
 
-g = graph_tool.load_graph_from_csv("edgelist.csv", directed = True,
-                                   csv_options = {'delimiter': ' ',
-                                                  'skipinitialspace': True})
 g.set_directed(False)
 
 for v in g.vertices():