吴恩达Machine Learning课程学习笔记5 无监督学习 推荐系统和强化学习（P114-125）

新年好哇！祝大家蛇年大吉！

本篇笔记是第三课（Unsupervised Learning Recommender Systems and Reinforcement learning 无监督学习 推荐系统和强化学习），本篇笔记是关于推荐系统,结合视频、ppt进行注释并补充笔记，欢迎交流学习，理解不到位的地方敬请指出，教程视频来自B站（P114-125）

https://www.bilibili.com/video/BV1Bq421A74G/?buvid=Z14EDF1C5DBE11C64D4E9707BCEC62743AED&is_story_h5=false&mid=mmDXd2ZzgQLEUfEbFCZCCw%3D%3D&plat_id=114&share_from=ugc&share_medium=iphone&share_plat=ios&share_source=WEIXIN&share_tag=s_i×tamp=1734580797&unique_k=NbdxkL0&up_id=1232187625&spm_id_from=333.788.videopod.episodeshttps://www.bilibili.com/video/BV1Bq421A74G/?buvid=Z14EDF1C5DBE11C64D4E9707BCEC62743AED&is_story_h5=false&mid=mmDXd2ZzgQLEUfEbFCZCCw%3D%3D&plat_id=114&share_from=ugc&share_medium=iphone&share_plat=ios&share_source=WEIXIN&share_tag=s_i×tamp=1734580797&unique_k=NbdxkL0&up_id=1232187625&spm_id_from=333.788.videopod.episodeshttps://www.bilibili.com/video/BV1Bq421A74G/?buvid=Z14EDF1C5DBE11C64D4E9707BCEC62743AED&is_story_h5=false&mid=mmDXd2ZzgQLEUfEbFCZCCw%3D%3D&plat_id=114&share_from=ugc&share_medium=iphone&share_plat=ios&share_source=WEIXIN&share_tag=s_i×tamp=1734580797&unique_k=NbdxkL0&up_id=1232187625&spm_id_from=333.788.videopod.episodeshttps://www.bilibili.com/video/BV1Bq421A74G/?buvid=Z14EDF1C5DBE11C64D4E9707BCEC62743AED&is_story_h5=false&mid=mmDXd2ZzgQLEUfEbFCZCCw%3D%3D&plat_id=114&share_from=ugc&share_medium=iphone&share_plat=ios&share_source=WEIXIN&share_tag=s_i×tamp=1734580797&unique_k=NbdxkL0&up_id=1232187625&spm_id_from=333.788.videopod.episodeshttps://www.bilibili.com/video/BV1Bq421A74G/?buvid=Z14EDF1C5DBE11C64D4E9707BCEC62743AED&is_story_h5=false&mid=mmDXd2ZzgQLEUfEbFCZCCw%3D%3D&plat_id=114&share_from=ugc&share_medium=iphone&share_plat=ios&share_source=WEIXIN&share_tag=s_i×tamp=1734580797&unique_k=NbdxkL0&up_id=1232187625&spm_id_from=333.788.videopod.episodeshttps://www.bilibili.com/video/BV1Bq421A74G/?buvid=Z14EDF1C5DBE11C64D4E9707BCEC62743AED&is_story_h5=false&mid=mmDXd2ZzgQLEUfEbFCZCCw%3D%3D&plat_id=114&share_from=ugc&share_medium=iphone&share_plat=ios&share_source=WEIXIN&share_tag=s_i×tamp=1734580797&unique_k=NbdxkL0&up_id=1232187625&spm_id_from=333.788.videopod.episodeshttps://www.bilibili.com/video/BV1Bq421A74G/?buvid=Z14EDF1C5DBE11C64D4E9707BCEC62743AED&is_story_h5=false&mid=mmDXd2ZzgQLEUfEbFCZCCw%3D%3D&plat_id=114&share_from=ugc&share_medium=iphone&share_plat=ios&share_source=WEIXIN&share_tag=s_i×tamp=1734580797&unique_k=NbdxkL0&up_id=1232187625&spm_id_from=333.788.videopod.episodeshttps://www.bilibili.com/video/BV1Bq421A74G/?buvid=Z14EDF1C5DBE11C64D4E9707BCEC62743AED&is_story_h5=false&mid=mmDXd2ZzgQLEUfEbFCZCCw%3D%3D&plat_id=114&share_from=ugc&share_medium=iphone&share_plat=ios&share_source=WEIXIN&share_tag=s_i×tamp=1734580797&unique_k=NbdxkL0&up_id=1232187625&spm_id_from=333.788.videopod.episodeshttps://www.bilibili.com/video/BV1Bq421A74G/?buvid=Z14EDF1C5DBE11C64D4E9707BCEC62743AED&is_story_h5=false&mid=mmDXd2ZzgQLEUfEbFCZCCw%3D%3D&plat_id=114&share_from=ugc&share_medium=iphone&share_plat=ios&share_source=WEIXIN&share_tag=s_i×tamp=1734580797&unique_k=NbdxkL0&up_id=1232187625&spm_id_from=333.788.videopod.episodeshttps://www.bilibili.com/video/BV1Bq421A74G/?buvid=Z14EDF1C5DBE11C64D4E9707BCEC62743AED&is_story_h5=false&mid=mmDXd2ZzgQLEUfEbFCZCCw%3D%3D&plat_id=114&share_from=ugc&share_medium=iphone&share_plat=ios&share_source=WEIXIN&share_tag=s_i×tamp=1734580797&unique_k=NbdxkL0&up_id=1232187625&spm_