在推荐实验室中使用userid进行预测

Question

我有一个相当简单的推荐问题:我希望在R中使用recommenderlab构建一个混合推荐程序，在这里，我推荐MovieLense数据集中已经喜欢的电影，以及流行电影和一些随机电影。

library(recommenderlab)

data("MovieLense")

MovieLense100 <- MovieLense[rowCounts(MovieLense) > 100,]
train <- MovieLense100[1:100]
test <- MovieLense100[101:103]

## mix popular movies with a random recommendations for diversity and
## rerecommend some movies the user liked.
recom <- HybridRecommender(
  Recommender(train, method = "POPULAR"),
  Recommender(train, method = "RANDOM"),
  Recommender(train, method = "RERECOMMEND"),
  weights = c(.6, .1, .3)
)

当我训练了这个模型后，我想用userId“预测”给定用户的电影。Recommenderlab文档表明，只要用户in在培训数据中，这是可能的。但是，当我尝试在userid中使用newdata进行预测时，会得到以下错误消息：

as(predict(object = recom, newdata = 1), "list")
#> Error in object@predict(object@model, newdata, n = n, data = data, type = type, : If newdata is a user id then data needes to be the training dataset.

公平地说，我尝试用一个向量：

as(predict(recom, newdata = c(1,5)), "list")
#> Error in object@predict(object@model, newdata, n = n, data = data, type = type, : If newdata is a user id then data needes to be the training dataset.

不知道这个错误信息是什么意思。有人知道吗？

Answer 1

您只需要从培训数据集中精确地说明您正在向用户推荐项目，如下所示：

> as(predict(recom, 1, data = train), "list")
$`1`
 [1] "Hearts and Minds (1996)"                     "Boys, Les (1997)"                            "Great Day in Harlem, A (1994)"              
 [4] "Dangerous Beauty (1998)"                     "Tough and Deadly (1995)"                     "Two or Three Things I Know About Her (1966)"
 [7] "Santa with Muscles (1996)"                   "Margaret's Museum (1995)"                    "Brassed Off (1996)"                         
[10] "Thousand Acres, A (1997)"                   

> as(predict(recom, 1:10, data = train), "list")
$`1`
 [1] "Dangerous Beauty (1998)"                     "Great Day in Harlem, A (1994)"               "Hearts and Minds (1996)"                    
 [4] "Boys, Les (1997)"                            "Santa with Muscles (1996)"                   "Two or Three Things I Know About Her (1966)"
 [7] "Tough and Deadly (1995)"                     "Saint of Fort Washington, The (1993)"        "Whole Wide World, The (1996)"               
[10] "Margaret's Museum (1995)"                   

$`5`
 [1] "Boys, Les (1997)"                            "Two or Three Things I Know About Her (1966)" "Santa with Muscles (1996)"                  
 [4] "Dangerous Beauty (1998)"                     "Great Day in Harlem, A (1994)"               "Whole Wide World, The (1996)"               
 [7] "Hearts and Minds (1996)"                     "Brassed Off (1996)"                          "Saint of Fort Washington, The (1993)"       
[10] "Celestial Clockwork (1994)"                 

$`6`
 [1] "Dangerous Beauty (1998)"                     "Two or Three Things I Know About Her (1966)" "Santa with Muscles (1996)"                  
 [4] "Tough and Deadly (1995)"                     "Brassed Off (1996)"                          "Crooklyn (1994)"                            
 [7] "Great Day in Harlem, A (1994)"               "Hearts and Minds (1996)"                     "Saint of Fort Washington, The (1993)"       
[10] "Boys, Les (1997)"                           

$`7`
 [1] "Two or Three Things I Know About Her (1966)" "Tough and Deadly (1995)"                     "Santa with Muscles (1996)"                  
 [4] "Dangerous Beauty (1998)"                     "Hearts and Minds (1996)"                     "Great Day in Harlem, A (1994)"              
 [7] "Boys, Les (1997)"                            "Brassed Off (1996)"                          "Margaret's Museum (1995)"                   
[10] "Crooklyn (1994)"                            

$`10`
 [1] "Dangerous Beauty (1998)"                     "Great Day in Harlem, A (1994)"               "Hearts and Minds (1996)"                    
 [4] "Tough and Deadly (1995)"                     "Two or Three Things I Know About Her (1966)" "Boys, Les (1997)"                           
 [7] "Santa with Muscles (1996)"                   "Brassed Off (1996)"                          "Margaret's Museum (1995)"                   
[10] "Crooklyn (1994)"                            

$`11`
 [1] "Two or Three Things I Know About Her (1966)" "Hearts and Minds (1996)"                     "Great Day in Harlem, A (1994)"              
 [4] "Tough and Deadly (1995)"                     "Brassed Off (1996)"                          "Dangerous Beauty (1998)"                    
 [7] "Boys, Les (1997)"                            "Santa with Muscles (1996)"                   "Thousand Acres, A (1997)"                   
[10] "Horse Whisperer, The (1998)"                

$`13`
 [1] "Santa with Muscles (1996)"        "Brassed Off (1996)"               "Tough and Deadly (1995)"          "Boys, Les (1997)"                
 [5] "Thousand Acres, A (1997)"         "Margaret's Museum (1995)"         "Total Eclipse (1995)"             "Love! Valour! Compassion! (1997)"
 [9] "Withnail and I (1987)"            "Prefontaine (1997)"              

$`15`
 [1] "Two or Three Things I Know About Her (1966)" "Boys, Les (1997)"                            "Great Day in Harlem, A (1994)"              
 [4] "Tough and Deadly (1995)"                     "Dangerous Beauty (1998)"                     "Saint of Fort Washington, The (1993)"       
 [7] "Santa with Muscles (1996)"                   "Hearts and Minds (1996)"                     "Celestial Clockwork (1994)"                 
[10] "Whole Wide World, The (1996)"               

$`16`
 [1] "Great Day in Harlem, A (1994)"               "Dangerous Beauty (1998)"                     "Hearts and Minds (1996)"                    
 [4] "Two or Three Things I Know About Her (1966)" "Boys, Les (1997)"                            "Santa with Muscles (1996)"                  
 [7] "Tough and Deadly (1995)"                     "Brassed Off (1996)"                          "Crooklyn (1994)"                            
[10] "Thousand Acres, A (1997)"                   

$`18`
 [1] "Great Day in Harlem, A (1994)"               "Two or Three Things I Know About Her (1966)" "Dangerous Beauty (1998)"                    
 [4] "Hearts and Minds (1996)"                     "Santa with Muscles (1996)"                   "Tough and Deadly (1995)"                    
 [7] "Boys, Les (1997)"                            "Whole Wide World, The (1996)"                "Margaret's Museum (1995)"                   
[10] "Saint of Fort Washington, The (1993)" 

否则，我们不知道您指的是什么用户的预测函数。

您还可以对测试数据进行如下预测：

> as(predict(recom, test), "list")