add autodl

AutoDL-Projects/xautodl/xmisc/sampler_utils.py

@@ -0,0 +1,32 @@
+#####################################################
+# Copyright (c) Xuanyi Dong [GitHub D-X-Y], 2021.06 #
+#####################################################
+import random
+
+
+class BatchSampler:
+    """A batch sampler used for single machine training."""
+
+    def __init__(self, dataset, batch, steps):
+        self._num_per_epoch = len(dataset)
+        self._iter_per_epoch = self._num_per_epoch // batch
+        self._steps = steps
+        self._batch = batch
+        if self._num_per_epoch < self._batch:
+            raise ValueError(
+                "The dataset size must be larger than batch={:}".format(batch)
+            )
+        self._indexes = list(range(self._num_per_epoch))
+
+    def __iter__(self):
+        """
+        yield a batch of indexes using random sampling
+        """
+        for i in range(self._steps):
+            if i % self._iter_per_epoch == 0:
+                random.shuffle(self._indexes)
+            j = i % self._iter_per_epoch
+            yield self._indexes[j * self._batch : (j + 1) * self._batch]
+
+    def __len__(self):
+        return self._steps