From c9ad16710875df6811db32660cfbb5ab8fa64045 Mon Sep 17 00:00:00 2001
From: Toru Ogawa <Hakuyume@users.noreply.github.com>
Date: Sat, 7 Oct 2017 11:11:02 +0900
Subject: [PATCH] use ConcatenatedDataset

---
 examples/faster_rcnn/train.py | 19 +------------------
 examples/ssd/train.py         | 19 +------------------
 2 files changed, 2 insertions(+), 36 deletions(-)

diff --git a/examples/faster_rcnn/train.py b/examples/faster_rcnn/train.py
index 1fa7ed16b7..aad30113f2 100644
--- a/examples/faster_rcnn/train.py
+++ b/examples/faster_rcnn/train.py
@@ -4,6 +4,7 @@
 import numpy as np
 
 import chainer
+from chainer.datasets import ConcatenatedDataset
 from chainer.datasets import TransformDataset
 from chainer import training
 from chainer.training import extensions
@@ -17,24 +18,6 @@
 from chainercv import transforms
 
 
-class ConcatenatedDataset(chainer.dataset.DatasetMixin):
-
-    def __init__(self, *datasets):
-        self._datasets = datasets
-
-    def __len__(self):
-        return sum(len(dataset) for dataset in self._datasets)
-
-    def get_example(self, i):
-        if i < 0:
-            raise IndexError
-        for dataset in self._datasets:
-            if i < len(dataset):
-                return dataset[i]
-            i -= len(dataset)
-        raise IndexError
-
-
 class Transform(object):
 
     def __init__(self, faster_rcnn):
diff --git a/examples/ssd/train.py b/examples/ssd/train.py
index ce1822aa25..8d89f4f6d6 100644
--- a/examples/ssd/train.py
+++ b/examples/ssd/train.py
@@ -3,6 +3,7 @@
 import numpy as np
 
 import chainer
+from chainer.datasets import ConcatenatedDataset
 from chainer.datasets import TransformDataset
 from chainer.optimizer import WeightDecay
 from chainer import serializers
@@ -24,24 +25,6 @@
 from chainercv.links.model.ssd import resize_with_random_interpolation
 
 
-class ConcatenatedDataset(chainer.dataset.DatasetMixin):
-
-    def __init__(self, *datasets):
-        self._datasets = datasets
-
-    def __len__(self):
-        return sum(len(dataset) for dataset in self._datasets)
-
-    def get_example(self, i):
-        if i < 0:
-            raise IndexError
-        for dataset in self._datasets:
-            if i < len(dataset):
-                return dataset[i]
-            i -= len(dataset)
-        raise IndexError
-
-
 class MultiboxTrainChain(chainer.Chain):
 
     def __init__(self, model, alpha=1, k=3):