r - 如何从另一个向量中获取包含具有相应值的字符的矩阵的行总和

Question

您好，我从我的数据中提取了这一列:

x <- data.frame(Category=factor(c("xxyyxyxyx", "xxyyyyxyx", "xxyyxyxyy",
           "yxyyxyxyx", "xxyyxyyyx")))
> x
  Category
1 xxyyxyxyx
2 xxyyyyxyx
3 xxyyxyxyy
4 yxyyxyxyx
5 xxyyxyyyx 

我必须计算每行中每三个字符产生的相应行总和，所以我生成了这个矩阵:

xx <- t(apply(x, 1, function(x){strsplit(gsub("([[:alnum:]]{3})", "\\1 ", x), " ")[[1]]}))

> xx

         [,1]  [,2]  [,3] 
     [1,] "xxy" "yxy" "xyx"
     [2,] "xxy" "yyy" "xyx"
     [3,] "xxy" "yxy" "xyy"
     [4,] "yxy" "yxy" "xyx"
     [5,] "xxy" "yxy" "yyx"

每个 xx 单元格对应于此向量中给定的值

matval=c("xxy"=3, "yxy"=2, "xyx"=7, "xyy"=5, "yyx"=12, "yyy"= 4)

我想基于矩阵 xx 在矩阵 x 中添加一个包含每一行总和的列，即

x

   Category    RowSum
 1 xxyyxyxyx     12
 2 xxyyyyxyx     14
 3 xxyyxyxyy     10
 4 yxyyxyxyx     11
 5 xxyyxyyyx     17

非常感谢!

Answer 1

我们可以使用键/值索引替换'xx'中的值并获得rowSums

x$RowSum <- rowSums(`dim<-`(matval[xx], dim(xx)))

---

'xx' 也可以使用 strsplit

创建

 do.call(rbind, strsplit(as.character(x$Category), "(?<=.{3})", perl = TRUE))