【数据挖掘】国科大刘莹老师数据挖掘课程作业 —— 第三次作业

使用与 User 2 最相似的三个 User 预测 User 2 的 Product 2。

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begin{align} bar r_{rm User ;1} &= frac{1}{4}(1+1+5+3) = frac{5}{2} \ bar r_{rm User ;2} &= frac{1}{3} (3+5+3) = 4 \ bar r_{rm User ;3} &= frac{1}{4} (1+3+1+1) = frac{3}{2} \ bar r_{rm User ;5} &= frac{1}{4}(2+2+2+4) = frac{5}{2} end{align}

rˉUser1​rˉUser2​rˉUser3​rˉUser5​​=41​(1+1+5+3)=25​=31​(3+5+3)=4=41​(1+3+1+1)=23​=41​(2+2+2+4)=25​​​

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≈

3.851

begin{align} r_{rm User ;2, Product ;2} &= bar r_{rm User ;2} + frac{{{rm sim(1,2)}(r_{rm User; 1, Product;2}- bar r_{rm User; 1}) } + {{rm sim(3,2)}(r_{rm User; 3, Product;2}- bar r_{rm User; 3})} + {{rm sim(5,2)}(r_{rm User; 5, Product;2}- bar r_{rm User; 5}) }}{rm sim(1,2) + sim(3,2)+ sim(5,2)} \ &≈ 3.851 end{align}

rUser2,Product2​​=rˉUser2​+sim(1,2)+sim(3,2)+sim(5,2)sim(1,2)(rUser1,Product2​−rˉUser1​)+sim(3,2)(rUser3,Product2​−rˉUser3​)+sim(5,2)(rUser5,Product2​−rˉUser5​)​≈3.851​​