Question

假设我有以下三列数据框。

data = data.frame(id=c(1:10), interest_1=c("food","","","drugs","beer","soda","","","drugs","sports"),
                  interest_2=c("fruits","car","jeans","","","","soda","shoes","","drugs"),
                  interest_3=c("","","","","soda","sports","","","",""))

data

我想得到每一行的数量。

以下事件，其中食物是兴趣_1，水果是兴趣_2，没有兴趣_3仅发生一次。

   id interest_1 interest_2 interest_3
1   1       food     fruits

以下事件，其中药物是兴趣_1，没有兴趣_2或者兴趣_3出现两次。

 id interest_1 interest_2 interest_3
  4      drugs                      
  9      drugs

我想计算每次发生的次数。我该怎么做呢？

输出应如下所示：

 interest_1 interest_2 interest_3   count
     food     fruits                 1
                        car          1  
              jeans                  1
     drugs                           2

Answer 1

> aggregate(id~.,data,length)
  interest_1 interest_2 interest_3 id
1      drugs                        2
2                   car             1
3     sports      drugs             1
4       food     fruits             1
5                 jeans             1
6                 shoes             1
7                  soda             1
8       beer                  soda  1
9       soda                sports  1

基本上，这意味着：将函数length应用于由其他列的每个组合的id值组成的向量。

Answer 2

require(plyr)
ddply(data, .(interest_1, interest_2, interest_3), c("nrow"))

R中的行频计数

2 个答案: