在r中连接两个字符串列表并附加索引

这是我的样本：

stringa = c("a","b","c")
stringb = c("high","low","average")
index = c(1,2,3)

data <- data.frame(stringa,stringb,index)

对于“a高”、“b低”、“c平均值”，您可以执行以下操作：

stringa = c("a","b","c")
stringb = c("high","low","average")
index = c(1,2,3)
data.frame(concatenated = paste(stringa, stringb),index)
  concatenated
1    a high
2    b low
3    c average

对于stringa和stringb的完整排列：

stringa = c("a","b","c")
stringb = c("high","low","average")
data.frame(concatenated = c(outer(stringa, stringb, paste) ) )
    concatenated
1       a high
2       b high
3       c high
...
9    c average

如果要显式添加行索引：

df = data.frame(concatenated = c(outer(stringa, stringb, paste) ) )
df$index = rownames(df)
df 
  concatenated index
1       a high     1
2       b high     2
3       c high     3
...
9    c average     9

---

怎么搞的？不是如预期的那样吗？我还需要将“a”与“low”和“average”连接起来

df = data.frame(concatenated = c(outer(stringa, stringb, paste) ) )
df$index = rownames(df)
df 
  concatenated index
1       a high     1
2       b high     2
3       c high     3
...
9    c average     9