add support for lammps_map_atom() in python module

python/lammps/core.py

@@ -269,6 +269,9 @@ class lammps(object):
     self.lib.lammps_extract_global_datatype.restype = c_int
     self.lib.lammps_extract_compute.argtypes = [c_void_p, c_char_p, c_int, c_int]
 
+    self.lib.lammps_map_atom.argtypes = [c_void_p, c_void_p]
+    self.lib.lammps_map_atom.restype = c_int
+
     self.lib.lammps_get_thermo.argtypes = [c_void_p, c_char_p]
     self.lib.lammps_get_thermo.restype = c_double
 
@@ -928,6 +931,24 @@ class lammps(object):
       else: return target_type(ptr[0])
     return None
 
+  # -------------------------------------------------------------------------
+  # map global atom ID to local atom index
+
+  def map_atom(self, id):
+    """Map a global atom ID (aka tag) to the local atom indx
+
+    This is a wrapper around the :cpp:func:`lammps_map_atom`
+    function of the C-library interface.
+
+    :param id: atom ID
+    :type id:  int
+    :return: local index
+    :rtype: int
+    """
+
+    tag = self.c_tagint(id)
+    return self.lib.lammps_map_atom(self.lmp, pointer(tag))
+
   # -------------------------------------------------------------------------
   # extract per-atom info datatype