决策树、随机森林、bagging、boosting、adaboost、gbdt、xgboost总结
机器学习算法与Python实战
共 5733字,需浏览 12分钟
· 2021-12-18
作者:ChrisCao
https://zhuanlan.zhihu.com/p/75468124
一. 决策树
![](https://filescdn.proginn.com/7074af9908c06ed52a67164f077dd7f9/969754c2b0d5034782df66874fb68255.webp)
1.ID3算法:以信息增益为准则来选择最优划分属性
![](https://filescdn.proginn.com/55d835c4f4d1880fa3836cfd714f1790/f728b12b87d3f9f23c51bcdc035496da.webp)
![](https://filescdn.proginn.com/28b60adcd837c7dd7ac6af26a0581eae/4513699650500cb6aeb5880829179406.webp)
![](https://filescdn.proginn.com/c292a927b6eab780a21bd32161d180c7/ef9f8c6f21af505c625acc17ce13a159.webp)
![](https://filescdn.proginn.com/6eaea8c688ec13d8499a4a77c53b9728/bd782ed4c037b2d119720b24d1765ea5.webp)
![](https://filescdn.proginn.com/8eef3ac7358426f78daa65d4cafaf77e/926149cb66316cb5ba4f66e33676fb4a.webp)
![](https://filescdn.proginn.com/e3ec01e154d72e1c218ef16bd1b34d17/7d76a05cc3f627ba014fd23ea4e1f3b6.webp)
2.C4.5基于信息增益率准则 选择最有分割属性的算法
![](https://filescdn.proginn.com/4ae0c19244703dfd1c69e1eea7d45450/d5e9fe2199141a8c0525c9747a80a82c.webp)
![](https://filescdn.proginn.com/19f241ba746567925a3e219f7776972c/10137a78ced6ad30553a46f31e65d851.webp)
3.CART:以基尼系数为准则选择最优划分属性,可用于分类和回归
![](https://filescdn.proginn.com/04cc3c1d8236e7ae842ba81025b04180/e26faa6ac5ed194363107fe0d63581a6.webp)
二.随机森林
1.构建组合分类器的好处:
![](https://filescdn.proginn.com/2fb95fa003b87d02e33721ba22a538b2/d13d589255fd7e90302e8759cf941518.webp)
![](https://filescdn.proginn.com/26f13618c86d1292ee542e6581108f28/f5173cba4035a576d5c8814109044efb.webp)
![](https://filescdn.proginn.com/de59315cc673cf360abe5e8ea6788a26/b69730475e0da0930ae79128baebcf6d.webp)
![](https://filescdn.proginn.com/9c5f336f56bdb552547222ed4ca7245a/dff97375a34d0ce2a0a51c5ab62cc6a6.webp)
![](https://filescdn.proginn.com/0eee56078888d15edd4b148c7b095d71/4f0cb49dba6678940a37f825ba976e21.webp)
三、GBDT和XGBoost
1.在讲GBDT和XGBoost之前先补充Bagging和Boosting的知识。
![](https://filescdn.proginn.com/1f1e9cc1d1c44fee1f6ac37d6e17c249/900e2052e12e4c282d861ce901b66585.webp)
![](https://filescdn.proginn.com/21f5df83d8db7e498874625bab9eb5c9/391f89ed2adefe369b81ffb75351485b.webp)
![](https://filescdn.proginn.com/791e788efd4fa59a1032c9e79019f680/1c5442e05e629d0ab51e1898258fbbe9.webp)
![](https://filescdn.proginn.com/2878d07019f8b08d6c70e476914a896e/3606ca505fc630dffd54f97a5a466c60.webp)
![](https://filescdn.proginn.com/3702a752a46191cd88f87adc20ab31c1/258dad7eaa99ea0599c205eb2f914882.webp)
![](https://filescdn.proginn.com/d9c6553a7c52cec0f68fe83cc1cdccf8/c35a4e68b61b1b61997b3b5f897e48c0.webp)
2.GBDT
![](https://filescdn.proginn.com/06249cb6d8a8b3cb43ed7f52ddaa3eaa/532b66df35b3d552f1bf5a0a9842e4ef.webp)
![](https://filescdn.proginn.com/62859fcd938044107a38629151d8ee64/994ed25b0a03623115375e90a3067447.webp)
3.XGBoost
![](https://filescdn.proginn.com/41f9bdee27096163bce6e0241cdd4f02/0b771b5fea576a3a38ff0c971632147d.webp)
![](https://filescdn.proginn.com/23bd3326c2a61e3255a17883f8a0ebfa/bf6480e64abc30b4c1e568e0c3f32f7a.webp)
![](https://filescdn.proginn.com/88675fcef0e1af83afc2b5a9a7705a6b/c58480e39e237c61baa24ce3788c1adb.webp)
![](https://filescdn.proginn.com/7145a59b43f7948dacd8f8a0701e07aa/6842b54f45301ee2162e7a43a1d000d1.webp)
![](https://filescdn.proginn.com/4836590997abfb0ad9431c0f948e1130/46b7df4a4111059071b543b38bde05b8.webp)
![](https://filescdn.proginn.com/2c4a3f04ed02fabc20355c59f347c063/76787eff34004bf3de69554e35362c07.webp)
![](https://filescdn.proginn.com/f238df0d0de17b894558948b2f893d80/7dfc25449622c780d0997a367692ba22.webp)
![](https://filescdn.proginn.com/137139ef236db8af27f3871855b29a15/74b0ba1dd523cff3af953f34110e0f19.webp)
point的候选,遍历所有的候选分裂点来找到最佳分裂点。
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