r语言 - 计算多个向量之间的成对相交

Question

我有多个数据帧，看起来像这样:

>df1
NAME    
Josh
Sarah
Sammy
Jake
>df2
NAME    
Josh
Sarah
Sammy
Mark
>df3
NAME    
Josh
Michael
Mike
Adam 
>df4
NAME
Josh
Michael
Mike
Adam

我想创建一个包含这些dfs的交点个数的新数据帧，就像这样

>df.final
df1 df2 df3 df4
df1   4   3   1   4
df2   3   4   1   1
df3   1   1   4   4
df4   1   1   4   4

我怎样才能做到这一点?从本质上讲，我希望自动化intersect()和length()功能，而无需手动输入它们。

#create the data
df1 <- data.frame(NAME=c("Josh", "Sarah", "Sammy", "Jake"))
df2 <- data.frame(NAME=c("Josh", "Sarah", "Sammy", "Mark"))
df3 <- data.frame(NAME=c("Josh", "Michael", "Mike", "Adam"))
df4 <- data.frame(NAME=c("Josh", "Michael", "Mike", "Adam"))

Answer 1

#create the data
df1 <- data.frame(NAME=c("Josh", "Sarah", "Sammy", "Jake"))
df2 <- data.frame(NAME=c("Josh", "Sarah", "Sammy", "Mark"))
df3 <- data.frame(NAME=c("Josh", "Michael", "Mike", "Adam"))
df4 <- data.frame(NAME=c("Josh", "Michael", "Mike", "Adam"))
l <- c("df1","df2","df3","df4")
names(l) <- l
result <- outer(mget(l),mget(l), function(x,y) 
mapply(function(x,y) length(intersect(x$NAME , y$NAME)),x,y ) )
result
#>     df1 df2 df3 df4
#> df1   4   3   1   1
#> df2   3   4   1   1
#> df3   1   1   4   4
#> df4   1   1   4   4

编辑

矢量化也可以:

result <- outer(mget(l),mget(l), Vectorize(
function(x,y) length(intersect(x$NAME , y$NAME))))