将数据框中的两列与另一个数据框中的多列相匹配，返回第一个匹配列

Question

我正在尝试将数据帧中的两列与另一个数据帧匹配，并且我希望返回的值是第二个数据帧中首先匹配两个初始列的值。

例如： 我想采用以下数据框：

Fasta<-c("X1","X1","X2","X2","X3","X3")
Species<-c("Kiwi","Chicken","Weta","Cricket","Tuatara","Gecko")
testdata<-as.data.frame(cbind(Fasta,Species))
testdata<-aggregate(Species ~ Fasta, testdata, I)
testdata<-aggregate(Species ~ Fasta, testdata, I)

Fasta    Species1 Species2

X1       Kiwi      Chicken
X2       Weta      Cricket
X3       Tuatara   Gecko

以下是我的第二个数据框

Species<-c("Kiwi","Chicken","Weta","Cricket","Frog","Gecko")
Genus<-c("Orn","Norn","Genus2","Genus2","Spec","NoSpec")
Order<-c("Bird","Bird","Order2","Order2","Norder","Geckn")
Kingdom<-rep("Animal",each=6)
lookup<-data.frame(cbind(Species,Genus,Order,Kingdom))

Species Genus   Order   Kingdom

Kiwi    Orn     Bird    Animal
Chicken Norn    Bird    Animal
Weta    Genus2  Order2  Animal
Cricket Genus2  Order2  Animal
Frog    Spec    Norder  Animal
Gecko   NoSpec  Geckn   Animal

我想在第二个数据框中找到匹配 Species1 和 Species2 的第一列并返回其名称。理想情况下，这会给我以下输出：

Fasta   Species1    Species2    MatchLevel

X1      Kiwi        Chicken     Order
X2      Weta        Cricket     Genus
X3      Tuatara     Gecko       Kingdom

对不同格式的数据开放，

Answer 1

此函数利用了分类群的嵌套性（即，如果两个物种属于同一属，则它们必须处于相同的顺序等）。同一属中的两个物种得到 3 分，因为所有 3 个分类级别都匹配，如果在相同的顺序中，则为 2，如果在同一个界中，则为 1。也不可能匹配。

match2species <- function(a, b, lookup_table = lookup) {
  sp_a <- lookup_table[lookup_table$Species == a, ]
  sp_b <- lookup_table[lookup_table$Species == b, ]

  matches <- sum(sp_a[-1] == sp_b[-1])
  ifelse(matches > 0, c('Kingdom','Order','Genus')[matches], 'No match')

}

可以为数据框中的任何一对物种调用该函数。

> match2species('Chicken','Kiwi')
[1] "Order"
> match2species('Weta','Cricket')
[1] "Genus"
> match2species('Frog','Gecko')
[1] "Kingdom"