R从数据框中选择未出现在另一个数据框中的所有行

Question

我正试图解决一个棘手的R问题,我无法通过谷歌搜索关键字解决.具体来说,我试图采用一个子集,一个数据帧的值不会出现在另一个数据帧中.这是一个例子:

> test
      number    fruit     ID1  ID2 
item1 "number1" "apples"  "22" "33"
item2 "number2" "oranges" "13" "33"
item3 "number3" "peaches" "44" "25"
item4 "number4" "apples"  "12" "13"
> test2
      number    fruit     ID1   ID2 
item1 "number1" "papayas" "22"  "33"
item2 "number2" "oranges" "13"  "33"
item3 "number3" "peaches" "441" "25"
item4 "number4" "apples"  "123" "13"
item5 "number3" "peaches" "44"  "25"
item6 "number4" "apples"  "12"  "13"
item7 "number1" "apples"  "22"  "33"

我有两个数据框,test和test2,目标是选择test2中未出现在测试中的所有整行,即使某些值可能相同.

我想要的输出看起来像:

item1 "number1" "papayas" "22"  "33"
item2 "number3" "peaches" "441" "25"
item3 "number4" "apples"  "123" "13"

可能存在任意数量的行或列,但在我的特定情况下,一个数据帧是另一个的直接子集.

我已广泛使用R subset(),merge()和which()函数,但无法弄清楚如何组合使用它们,如果可能的话,可以得到我想要的东西.

编辑:这是我用来生成这两个表的R代码.

test <- data.frame(c("number1", "apples", 22, 33), c("number2", "oranges", 13, 33),
    c("number3", "peaches", 44, 25), c("number4", "apples", 12, 13))

test <- t(test)
rownames(test) = c("item1", "item2", "item3", "item4")
colnames(test) = c("number", "fruit", "ID1", "ID2")

test2 <- data.frame(data.frame(c("number1", "papayas", 22, 33), c("number2", "oranges", 13, 33),
    c("number3", "peaches", 441, 25), c("number4", "apples", 123, 13),c("number3", "peaches", 44, 25), c("number4", "apples", 12, 13)  ))

test2 <- t(test2)
rownames(test2) = c("item1", "item2", "item3", "item4", "item5", "item6")
colnames(test2) = c("number", "fruit", "ID1", "ID2")

提前致谢!

Answer 1

这是另一种方式:

x <- rbind(test2, test)
x[! duplicated(x, fromLast=TRUE) & seq(nrow(x)) <= nrow(test2), ]
#        number   fruit ID1 ID2
# item1 number1 papayas  22  33
# item3 number3 peaches 441  25
# item4 number4  apples 123  13

编辑:已修改以保留行名称.