allow to not specify field map list

if so find them in FIELD_MAP_PATH command instead

ess/lib_tw.py

@@ -33,7 +33,7 @@ class LATTICE:
     '''
         2015.10.14
     '''
-    def __init__(self,file_name_lat,file_name_fmap,freq=352.21,gamma=1.0):
+    def __init__(self,file_name_lat,file_name_fmap=[],freq=352.21,gamma=1.0):
 
         # In case file_name_fmap is str
         if isinstance(file_name_fmap,basestring): file_name_fmap=[file_name_fmap]
@@ -68,10 +68,11 @@ class LATTICE:
                         typ =lin.split()[0 ].upper()
                         para=lin.split()[1:]
                     # Map to a class
-                    if   typ == 'FIELD_MAP'   : lst.append(   FIELD_MAP(name,typ,para,dic_fmap))
-                    elif typ in dic_cls.keys(): lst.append(dic_cls[typ](name,typ,para)         )
-                    elif 'DIAG' in typ        : lst.append(        DIAG(name,typ,para)         )
-                    else                      : lst.append(        COMM(name,typ,para)         )
+                    if   typ == 'FIELD_MAP'      : lst.append(   FIELD_MAP(name,typ,para,dic_fmap))
+                    elif typ == 'FIELD_MAP_PATH' : _update_field_map_dict(dic_fmap,para[0])
+                    elif typ in dic_cls.keys()   : lst.append(dic_cls[typ](name,typ,para)         )
+                    elif 'DIAG' in typ           : lst.append(        DIAG(name,typ,para)         )
+                    else                         : lst.append(        COMM(name,typ,para)         )
                     # Break the loop
                     if typ=='END': break
 
@@ -938,6 +939,17 @@ def partran_end_all(file_name_in_all,file_name_out):
                 else            : file_out.write(' %10s'%lin[i])
             file_out.write('\n')
 
+
+
+def _update_field_map_dict(dictionary,folder_path):
+    import os
+    for filename in os.listdir(folder_path):
+        if filename.split('.')[-1]=='edz': # only 1D for now..
+            key=filename.split('.')[0]
+            if key not in dictionary: # do not override user selection
+                dictionary[key]=os.path.join(folder_path,filename)
+                print key,':',dictionary[key]
+
 #-------- Obsolete classes and functions
 
 #---- Old MATCH and LATTICE classes from the time of IPAC'15 (more complex)

ess/lib_tw_elem.py

@@ -90,6 +90,9 @@ class FIELD_MAP_DATA:
     '''
     def __init__(self,file_name):
 
+        if file_name.split('.')[-1]!='edz':
+            raise ValueError('Only 1D field maps (Ez) is supported for now')
+
         # Read file
         with open(file_name) as file: lin=file.readlines()