added distancebetween subcommand

Returns the distance between two systems.

README.md

@@ -23,7 +23,7 @@ optional arguments:
 ## explorationtools.py ##
 
 ```
-usage: explorationtools.py [-h] {bodycount} ...
+usage: explorationtools.py [-h] {bodycount,distancebetween} ...
 
 A collection of tools useful for exploration.
 
@@ -31,17 +31,31 @@ optional arguments:
   -h, --help            show this help message and exit
 
 subcommands:
-  {bodycount}  sub-command help
-    bodycount  Returns the number of bodies in a system. Will exit with code 1
-               on server error and code 2 if the system could not be found in
-               EDSM.
+  {bodycount,distancebetween}
+                        sub-command help
+    bodycount           Returns the number of bodies in a system. Will exit
+                        with code 1 on server error and code 2 if the system
+                        could not be found in EDSM.
+    distancebetween     Calculates the distance between two systems. Will exti
+                        with code 1 on server error and code 2 if (one of) the
+						systems could not be found on EDSM.
 ```
 
 ```
 usage: explorationtools.py bodycount [-h] system
 
 positional arguments:
-  system      the system in question
+  system
+
+optional arguments:
+  -h, --help  show this help message and exit
+```
+
+```
+usage: explorationtools.py distancebetween [-h] system system
+
+positional arguments:
+  system
 
 optional arguments:
   -h, --help  show this help message and exit

explorationtools.py

@@ -21,6 +21,22 @@ def getBodyCount(system):
     print(bodyCount)
     sys.exit(0)
 
+def distanceBetween(system1, system2):
+  try:
+    coords1 = System(system1).coords
+    coords2 = System(system2).coords
+  except ServerError as e:
+    print(e)
+    sys.exit(1)
+  except NotFoundError as e:
+    print(e)
+    syst.exit(2)
+  else:
+    print(int(round(math.sqrt( (coords1['x']-coords2['x'])**2
+        + (coords1['y']-coords2['y'])**2
+        + (coords1['z']-coords2['z'])**2 ),0)))
+    sys.exit(0)
+
 # ===========================================================================
 
 parser = argparse.ArgumentParser(description="A collection of tools useful for "
@@ -31,7 +47,13 @@ subparsers = parser.add_subparsers(title="subcommands", help="sub-command help",
 parser_bodycount = subparsers.add_parser("bodycount",
     help="Returns the number of bodies in a system. Will exit with code 1 on "
     + "server error and code 2 if the system could not be found in EDSM.")
-parser_bodycount.add_argument("system", nargs=1, help="the system in question")
+parser_bodycount.add_argument("system", nargs=1)
+
+parser_distance = subparsers.add_parser("distancebetween",
+    help="Calculates the distance between two systems. Will exti with code 1 "
+    + "on server error and code 2 if (one of) the systems could not be found "
+    + "on EDSM.")
+parser_distance.add_argument("system", nargs=2)
 
 args = parser.parse_args()
 
@@ -39,3 +61,5 @@ args = parser.parse_args()
 
 if args.subCommand == "bodycount":
   getBodyCount(args.system[0])
+elif args.subCommand == "distancebetween":
+  distanceBetween(args.system[0], args.system[1])