Misc dataset improvements

Summary: Pull Request resolved: https://github.com/pytorch/fairseq/pull/911

Differential Revision: D16536559

Pulled By: myleott

fbshipit-source-id: 7fe495054ce5b7658b1d3a43eca38c5858360236

fairseq/data/concat_dataset.py

@@ -8,6 +8,7 @@
 import bisect
 
 import numpy as np
+from torch.utils.data.dataloader import default_collate
 
 from . import FairseqDataset
 
@@ -50,7 +51,10 @@ class ConcatDataset(FairseqDataset):
 
     def collater(self, samples):
         # For now only supports datasets with same underlying collater implementations
-        return self.datasets[0].collater(samples)
+        if hasattr(self.datasets[0], 'collater'):
+            return self.datasets[0].collater(samples)
+        else:
+            return default_collate(samples)
 
     def size(self, idx: int):
         """

fairseq/data/dictionary.py

@@ -52,6 +52,9 @@ class Dictionary(object):
         """Returns the number of symbols in the dictionary"""
         return len(self.symbols)
 
+    def __contains__(self, sym):
+        return sym in self.indices
+
     def index(self, sym):
         """Returns the index of the specified symbol"""
         assert isinstance(sym, str)

fairseq/data/fairseq_dataset.py

@@ -5,6 +5,7 @@
 # the root directory of this source tree. An additional grant of patent rights
 # can be found in the PATENTS file in the same directory.
 
+import numpy as np
 import torch.utils.data
 
 
@@ -41,7 +42,7 @@ class FairseqDataset(torch.utils.data.Dataset):
     def ordered_indices(self):
         """Return an ordered list of indices. Batches will be constructed based
         on this order."""
-        raise NotImplementedError
+        return np.arange(len(self))
 
     @property
     def supports_prefetch(self):

fairseq/data/indexed_dataset.py

@@ -5,6 +5,7 @@
 # the root directory of this source tree. An additional grant of patent rights
 # can be found in the PATENTS file in the same directory.
 
+from functools import lru_cache
 import os
 import shutil
 import struct
@@ -146,6 +147,7 @@ class IndexedDataset(FairseqDataset):
         if self.data_file:
             self.data_file.close()
 
+    @lru_cache(maxsize=8)
     def __getitem__(self, i):
         if not self.data_file:
             self.read_data(self.path)
@@ -214,6 +216,7 @@ class IndexedCachedDataset(IndexedDataset):
             self.data_file.close()
             self.data_file = None
 
+    @lru_cache(maxsize=8)
     def __getitem__(self, i):
         self.check_index(i)
         tensor_size = self.sizes[self.dim_offsets[i]:self.dim_offsets[i + 1]]
@@ -255,6 +258,7 @@ class IndexedRawTextDataset(FairseqDataset):
         if i < 0 or i >= self.size:
             raise IndexError('index out of range')
 
+    @lru_cache(maxsize=8)
     def __getitem__(self, i):
         self.check_index(i)
         return self.tokens_list[i]
@@ -429,6 +433,7 @@ class MMapIndexedDataset(torch.utils.data.Dataset):
         def sizes(self):
             return self._sizes
 
+        @lru_cache(maxsize=8)
         def __getitem__(self, i):
             return self._pointers[i], self._sizes[i]
 
@@ -466,6 +471,7 @@ class MMapIndexedDataset(torch.utils.data.Dataset):
     def __len__(self):
         return len(self._index)
 
+    @lru_cache(maxsize=8)
     def __getitem__(self, i):
         ptr, size = self._index[i]
         np_array = np.frombuffer(self._bin_buffer, dtype=self._index.dtype, count=size, offset=ptr)