* Fix typo in usage example

* original MultiImageMixDataset code in mmdet

* Add MultiImageMixDataset unittests in test_dataset_wrapper

* fix lint error

* fix value name ann_file to ann_dir

* modify retrieve_data_cfg (#1)

* remove dynamic_scale & add palette

* modify retrieve_data_cfg method

* modify retrieve_data_cfg func

* fix error

* improve the unittests coverage

* fix unittests error

* Dataset (#2)

* add cfg-options

* Add unittest in test_build_dataset

* add blank line

* add blank line

* add a blank line

Co-authored-by: Miao Zheng <76149310+MeowZheng@users.noreply.github.com>

Co-authored-by: Younghoon-Lee <72462227+Younghoon-Lee@users.noreply.github.com>
Co-authored-by: MeowZheng <meowzheng@outlook.com>
Co-authored-by: Miao Zheng <76149310+MeowZheng@users.noreply.github.com>

* [Feature] Add tool to show origin or augmented train data

* [Feature] Support eval concate dataset

* Add docstring and modify evaluate of concate dataset

Signed-off-by: FreyWang <wangwxyz@qq.com>

* format concat dataset in subfolder of imgfile_prefix

Signed-off-by: FreyWang <wangwxyz@qq.com>

* add unittest of concate dataset

Signed-off-by: FreyWang <wangwxyz@qq.com>

* update unittest for eval dataset with CLASSES is None

Signed-off-by: FreyWang <wangwxyz@qq.com>

* [FIX] bug of generator,  which lead metric to nan when pre_eval=False

Signed-off-by: FreyWang <wangwxyz@qq.com>

* format code

Signed-off-by: FreyWang <wangwxyz@qq.com>

* add more unittest

* add more unittest

* optim concat dataset builder

* Add header for files

* Delete header in config files