Adding Attack Comparator Metric (pytorch#699)

Summary:
Pull Request resolved: pytorch#699

Add Attack Comparator metric as a robustness metrics to work with Captum perturbations as well as arbitrary transformations such as torchvision transforms.

Also adds support for summarizers / metrics to take floats as well as tensors.

Differential Revision: D29122998

fbshipit-source-id: f652e52dc373f248030cf97915b3f02f8f2ae55e

captum/attr/_utils/summarizer.py

@@ -2,6 +2,7 @@
 
 from typing import Dict, List, Optional, Tuple, Type, Union
 
+import torch
 from torch import Tensor
 
 from captum.attr._utils.stat import MSE, Count, Max, Mean, Min, Stat, StdDev, Sum, Var
@@ -76,6 +77,8 @@ def update(self, x: Union[Tensor, Tuple[Tensor, ...]]):
                         stats=stats, summary_stats_indices=self._summary_stats_indicies
                     )
                 )
+            if not isinstance(inp, torch.Tensor):
+                inp = torch.tensor(inp, dtype=torch.float)
             self._summarizers[i].update(inp)
 
     @property

captum/robust/__init__.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 
 from captum.robust._core.fgsm import FGSM  # noqa
+from captum.robust._core.metrics.attack_comparator import AttackComparator  # noqa
 from captum.robust._core.perturbation import Perturbation  # noqa
 from captum.robust._core.pgd import PGD  # noqa