r - 数据整理 - 将一列中的值与其他列中的值匹配

Question

我有以下格式的数据。

Noun   InCage   InHouse   InGarage   InTree
Bird   Bird     Dog       None       Cat
Cat    Bird     Dog       None       Cat
Dog    Bird     Dog       None       Cat

我想要这种格式:

Noun    Place
Bird    InCage
Cat     InTree
Dog     InHouse

除了编写一堆 if 语句之外，还有什么更聪明的方法可以做到这一点？

这是我提到的小例子的输出。

structure(list(
    Item = structure(c(2L, 3L, 1L), .Label = c("Bird", "Cat", 
    "Dog"), class = "factor"), InTree = structure(c(1L, 1L, 1L
    ), .Label = "Cat", class = "factor"), InHouse = structure(c(1L, 
    1L, 1L), .Label = "Dog", class = "factor"), InCage = structure(c(1L, 
    1L, 1L), .Label = "Bird", class = "factor"), InGarage = structure(c(1L, 
    1L, 1L), .Label = "none", class = "factor")), .Names = c("Item", "InTree", 
    "InHouse", "InCage", "InGarage"
    ), row.names = c(NA, -3L), class = "data.frame")

Answer 1

您可以使用 tidyr 和 dplyr。

首先我们收集，使数据变长，而不是变宽。然后我们过滤只保留项目和动物匹配的那些行:

library(tidyr)
library(dplyr)
dat %>% gather(place, animal, -Item) %>%
        filter(as.character(Item) == as.character(animal))

  Item   place animal
1  Cat  InTree    Cat
2  Dog InHouse    Dog
3 Bird  InCage   Bird