Updated dnarbd script to use pathlib and to use file's basename rather than full path

bin/dnarbd

@@ -3,6 +3,7 @@
 
 import argparse
 import re
+import pathlib
 from dnarbd.simulate import multiresolution_simulation as simulate
 
 parser = argparse.ArgumentParser(prog="dnarbd",
@@ -31,24 +32,23 @@ args = parser.parse_args()
 
 if __name__ == '__main__':
     
-    infile = args.input_file
+    infile = pathlib.Path(args.input_file)
     try:
-        re_result = re.match("(.*)\.([^.]+)",infile) 
-        prefix = re_result.group(1)
-        extension = re_result.group(2).lower()
+        prefix = infile.stem
+        extension = ".".join(infile.suffixes)
     except:
         raise Exception("Unrecognized input file '{}'".format(infile))
         
-    if extension == 'json':
+    if extension == '.json':
         from dnarbd.readers import read_cadnano as read_model
-    elif extension == 'ma':
+    elif extension == '.ma':
         from dnarbd.readers import read_vhelix as read_model
-    elif extension == 'pdb':
+    elif extension == '.pdb':
         from dnarbd.readers import read_atomic_pdb as read_model
     else:
         raise Exception("Unrecognized input file '{}'".format(infile))
                     
-    model = read_model( infile )
+    model = read_model( str(infile) )
 
     if args.output_prefix is not None:
         prefix = args.output_prefix