Add crude working collapse() method to SelectorMethods.

neurokernel/plsel.py

@@ -60,14 +60,17 @@ def __init__(self, s):
             self._str = copy.copy(s._str)
             self._expanded = copy.copy(s._expanded)
             self._max_levels = copy.copy(s._max_levels)
-        else:
-            assert isinstance(s, basestring) # python2 dependency
+        elif isinstance(s, basestring): # python2 dependency
             self._str = copy.copy(s)
 
             # Save expanded selector as tuple because it shouldn't need to be
             # modified after expansion:
             self._expanded = tuple(SelectorMethods.expand(s))
             self._max_levels = max(map(len, self._expanded))
+        else:
+            self._expanded = tuple(SelectorMethods.expand(s))
+            self._max_levels = max(map(len, self._expanded))
+            #XXX
 
     @property
     def nonempty(self):
@@ -913,7 +916,45 @@ def are_consecutive(int_list):
             return False
 
     @classmethod
-    def collapse(cls, id_list):
+    def collapse(cls, selector):
+        """
+        Collapse a selector into a single string.
+
+        Parameters
+        ----------
+        selector : iterable
+            Expanded selector. If the selector is a string, it is returned
+            unchanged.
+        
+        Returns
+        -------
+        s : str
+            String that comprises all identifiers in the specified expanded
+            selector.
+        """
+
+        if isinstance(selector, basestring):
+            return selector
+
+        result_list = []
+        for t in selector:
+            s = ''
+            for x in t:
+                if type(x) in [str, unicode, int]:
+                    s += '/'+str(x)
+                elif type(x) == slice:
+                    start = str(x.start) if x.start is not None else ''
+                    stop = str(x.stop) if x.stop is not None else ''
+                    s += '[%s:%s]' % (start, stop)
+                elif type(x) in [tuple, list]:
+                    s += '['+','.join(x)+']'
+                else:
+                    raise ValueError('invalid selector')
+            result_list.append(s)
+        return ','.join(result_list)
+
+    @classmethod
+    def _collapse(cls, id_list):
         """
         Collapse a list of identifiers into a selector string.
 
@@ -933,7 +974,9 @@ def collapse(cls, id_list):
         number of levels.
         """
 
-        # XXX doesn't collapse expanded selectors such as /foo/xxx,/bar/yyy properly
+        # XXX doesn't collapse expanded selectors such as /foo/xxx,/bar/yyy
+        # properly
+        raise NotImplemented('unfinished method - should eventually replace collapse()')
 
         # Can only collapse list identifiers that all have the same number of
         # levels: