Check if provided inputs of function are unused.

theano/compile/debugmode.py

@@ -1735,7 +1735,8 @@ class _Maker(FunctionMaker):  # inheritance buys a few helper functions
     def __init__(self, inputs, outputs, optimizer, mode,
             accept_inplace = False,
             function_builder = Function,
-            profile=None):
+            profile=None,
+            on_unused_input='raise'):
         """
         :type inputs: a list of SymbolicInput instances
 
@@ -1748,6 +1749,9 @@ class _Maker(FunctionMaker):  # inheritance buys a few helper functions
                     inplace operations in the graph from the inputs to
                     the outputs
 
+        :param on_unused_input: What to do if a variable in the 'inputs' list is
+        not used in the graph. Possible values are 'raise', 'warn', and 'ignore'.
+
         :note: this function sets TensorType.filter_checks_isfinite
         when `mode.check_isfinite` is True
 
@@ -1772,6 +1776,9 @@ class _Maker(FunctionMaker):  # inheritance buys a few helper functions
                                    [i.update for i in inputs
                                     if getattr(i, 'update', False)])
 
+        # Check if some input variables are unused
+        self._check_unused_inputs(inputs, outputs, on_unused_input)
+
 #TODO: REMOVE THIS CRUFT - it's complicated for SymbolicInputKits
         indices = [[input] + self.expand_in(input, _inputs) for input in inputs]
         expanded_inputs = reduce(list.__add__, [list(z)

theano/compile/function.py

@@ -13,7 +13,8 @@ from numpy import any #for to work in python 2.4
 
 def function(inputs, outputs=None, mode=None, updates=[], givens=[],
              no_default_updates=False, accept_inplace=False, name=None,
-             rebuild_strict=True, allow_input_downcast=None, profile=None):
+             rebuild_strict=True, allow_input_downcast=None, profile=None,
+             on_unused_input='raise'):
     """
     Return a callable object that will calculate `outputs` from `inputs`.
 
@@ -68,6 +69,9 @@ def function(inputs, outputs=None, mode=None, updates=[], givens=[],
     instance. If argument is `True` then a new ProfileStats instance will be
     used.  This profiling object will be available via self.profile.
 
+    :param on_unused_input: What to do if a variable in the 'inputs' list is
+    not used in the graph. Possible values are 'raise', 'warn', and 'ignore'.
+
     :note: Regarding givens: Be careful to make sure that these substitutions are
     independent--behaviour when Var1 of one pair appears in the graph leading to Var2 in
     another expression is undefined.  Replacements specified with givens are different from
@@ -111,6 +115,7 @@ def function(inputs, outputs=None, mode=None, updates=[], givens=[],
                 accept_inplace=accept_inplace,name=name,
                 rebuild_strict=rebuild_strict,
                 allow_input_downcast=allow_input_downcast,
+                on_unused_input=on_unused_input,
                 profile=profile)
     # We need to add the flag check_aliased inputs if we have any mutable or
     # borrowed used defined inputs

theano/compile/function_module.py

@@ -958,7 +958,7 @@ class FunctionMaker(object):
 
     def __init__(self, inputs, outputs,
             mode = None, accept_inplace = False, function_builder = Function,
-            profile=None):
+            profile=None, on_unused_input='raise'):
         """
         :type inputs: a list of SymbolicInput instances
 
@@ -972,6 +972,12 @@ class FunctionMaker(object):
 
         :param accept_inplace: True iff it is acceptable to have inplace operations
                     in the graph from the inputs to the outputs
+
+        :param on_unused_input: What to do if a variable in the 'inputs' list
+                is not used in the graph. Possible values are:
+                - 'raise' (default): raise an error
+                - 'warn': log a warning
+                - 'ignore': do not do anything
         """
         mode = mode_module.get_mode(mode)
 
@@ -1005,6 +1011,10 @@ class FunctionMaker(object):
         _inputs = gof.graph.inputs([o.variable for o in outputs] + [i.update
             for i in inputs if getattr(i, 'update', False)])
 
+
+        # Check if some input variables are unused
+        self._check_unused_inputs(inputs, outputs, on_unused_input)
+
         #TODO: REMOVE THIS CRUFT - it's complicated for SymbolicInputKits
         indices = [[input] + self.expand_in(input, _inputs) for input in inputs]
         expanded_inputs = reduce(list.__add__, [list(z) for x, y, z in indices], [])
@@ -1072,6 +1082,37 @@ class FunctionMaker(object):
                 (i.value != None and not isinstance(i.value, gof.Container) and i.update == None)
                     for i in self.inputs]
 
+    def _check_unused_inputs(self, inputs, outputs, on_unused_input):
+        if on_unused_input == 'ignore':
+            return
+
+        # There should be two categories of variables in inputs:
+        #  - variables that have to be provided (used_inputs)
+        #  - shared variables that will be updated
+        used_inputs = gof.graph.ancestors(
+                ([o.variable for o in outputs]
+                 + [i.update for i in inputs if getattr(i, 'update', False)]),
+                blockers=[i.variable for i in inputs])
+
+        msg = ("theano.function was asked to create a function computing "
+                "outputs given certain inputs, but one of the provided "
+                "input variables is not part of the computational graph "
+                "needed to compute the outputs: %s. To disable this %s, "
+                "you can pass the parameter on_unused_input='ignore' to "
+                "theano.function.")
+
+        for i in inputs:
+            if ((i.variable not in used_inputs) and (i.update is None)):
+                if on_unused_input == 'warn':
+                    warnings.warn(msg % (i.variable, 'warning'), stacklevel=5)
+                elif on_unused_input == 'raise':
+                    raise ValueError(msg % (i.variable, 'error'))
+                else:
+                    raise ValueError(("Invalid value for keyword "
+                        "on_unused_input of theano.function: '%s'. "
+                        "valid values are 'raise', 'warn', and 'ignore'."
+                        % on_unused_input))
+
     def create(self, input_storage=None, trustme=False):
         """
         Create a function.
@@ -1202,7 +1243,8 @@ def check_equal(x, y):
 def register_checker(checker):
     __checkers.insert(0, checker)
 
-def orig_function(inputs, outputs, mode=None, accept_inplace = False, name=None, profile=None):
+def orig_function(inputs, outputs, mode=None, accept_inplace = False,
+        name=None, profile=None, on_unused_input='raise'):
     """
     Return a Function that will calculate the outputs from the inputs.
 
@@ -1232,6 +1274,8 @@ def orig_function(inputs, outputs, mode=None, accept_inplace = False, name=None,
 
     :param profile: None or ProfileStats instance
 
+    :param on_unused_input: What to do if a variable in the 'inputs' list is
+    not used in the graph. Possible values are 'raise', 'warn', and 'ignore'.
     """
 
     #Every element of the input list will be upgraded to an `In` instance if necessary,
@@ -1262,7 +1306,8 @@ def orig_function(inputs, outputs, mode=None, accept_inplace = False, name=None,
                     outputs,
                     mode[0],
                     accept_inplace = accept_inplace,
-                    profile=profile).create(
+                    profile=profile,
+                    on_unused_input=on_unused_input).create(
                             defaults)
         else:
             if profile:
@@ -1292,7 +1337,8 @@ def orig_function(inputs, outputs, mode=None, accept_inplace = False, name=None,
                 outputs,
                 mode,
                 accept_inplace = accept_inplace,
-                profile=profile).create(
+                profile=profile,
+                on_unused_input=on_unused_input).create(
                         defaults)
 
     t2 = time.time()

theano/compile/pfunc.py

@@ -324,7 +324,7 @@ class Param(object):
 def pfunc(params, outputs=None, mode=None, updates=[], givens=[],
         no_default_updates=False, accept_inplace=False, name=None,
         rebuild_strict=True, allow_input_downcast=None,
-        profile=None):
+        profile=None, on_unused_input='raise'):
     """Function-constructor for graphs with shared variables.
 
     :type params: list of either Variable or Param instances.
@@ -372,6 +372,10 @@ def pfunc(params, outputs=None, mode=None, updates=[], givens=[],
     with that string as its `message` attribute.  This profiling object will be
     available via self.profile.
 
+    :type profile: str
+    :param profile: What to do if a variable in the 'inputs' list is not used
+    in the graph. Possible values are 'raise', 'warn', and 'ignore.
+
 
     :rtype: theano.compile.Function
     :returns: a callable object that will compute the outputs (given the inputs)
@@ -460,7 +464,8 @@ def pfunc(params, outputs=None, mode=None, updates=[], givens=[],
         inputs.append(si)
 
     return orig_function(inputs, cloned_outputs, mode,
-            accept_inplace=accept_inplace, name=name, profile=profile)
+            accept_inplace=accept_inplace, name=name, profile=profile,
+            on_unused_input=on_unused_input)
 
 
 def _pfunc_param_to_in(param, strict=False, allow_downcast=None):