Merge pull request !4340 from liubuyu/master

remove headers

fix iterator file

fix pr comments

fix new file

Merge pull request !3819 from jiangzhiwen/jzw/c_api_clue

Merge pull request !4219 from huanghui/add-op-unique

Merge pull request !3771 from cathwong/ckw_c_api_textfile_nosampler

Merge pull request !4268 from liubuyu/master

Merge pull request !4197 from YuJianfeng/adam_assign

Merge pull request !4220 from liyong126/minddataset_pk_num_samples

Merge pull request !4247 from 章一智/channel_swap_op

Merge pull request !3850 from islam_amin/randomaffine_op

Merge pull request !4250 from anthonyaje/fix_cpp_api_iterator

Merge pull request !3917 from luoyang/c-api

Merge pull request !3979 from MahdiRahmaniHanzaki/mixup

split into datasets

review fix

fix merge issues

fixed minddata lite build issues

Merge pull request !3944 from xiefangqi/md_new_api_CelebA

1. Check if data_ is null before compare it;
2. Always allocate an array for data_ even if size is zero.

Merge pull request !4019 from yao_yf/add_layout_in_stra_ckpt

Merge pull request !3977 from nhussain/multi_dim_concat_2

Merge pull request !3860 from xiefangqi/md_new_api_cocodataset

Merge pull request !3983 from huanghui/reduce-min-fission-pass

Merge pull request !3938 from liubuyu/master

Merge pull request !3807 from 徐永飞/master