add subset samplers (#888)

felixgwu · soumith · commit 5e7f5db3328a · 2017-03-02T09:26:10.000-05:00
diff --git a/torch/utils/data/sampler.py b/torch/utils/data/sampler.py
@@ -51,3 +51,20 @@ def __iter__(self):
 
     def __len__(self):
         return self.num_samples
+
+
+class SubsetRandomSampler(Sampler):
+    """Samples elements randomly from a given list of indices, without replacement.
+
+    Arguments:
+        indices (list): a list of indices
+    """
+
+    def __init__(self, indices):
+        self.indices = indices
+
+    def __iter__(self):
+        return (self.indices[i] for i in torch.randperm(len(self.indices)))
+
+    def __len__(self):
+        return len(self.indices)
