画韦恩图那么容易，为什么拿到指定元素却有问题

set.seed(123456789)
g1=LETTERS[sample(1:26,15)]
g2=LETTERS[sample(1:26,15)]
g3=LETTERS[sample(1:26,15)]
g4=LETTERS[sample(1:26,15)]
VENN.LIST=list(g1=g1,
               g2=g2,
               g3=g3,
               g4=g4)
VENN.LIST

> VENN.LIST
$g1
 [1] "T" "B" "G" "P" "K" "L" "M" "X" "U" "I" "R" "J" "O" "E" "S"

$g2
 [1] "F" "J" "O" "L" "Z" "D" "M" "N" "I" "T" "P" "B" "E" "C" "U"

$g3
 [1] "G" "M" "U" "F" "Y" "I" "W" "Q" "H" "J" "T" "A" "X" "E" "C"

$g4
 [1] "P" "M" "O" "N" "S" "Y" "Q" "K" "U" "W" "T" "G" "C" "F" "H"

require("VennDiagram") 
venn.plot <- venn.diagram(VENN.LIST , NULL, 
                          fill=c("red", "blue",'green','black'), 
                          alpha=c(0.5,0.5,0.5,0.5), cex = 2, cat.fontface=4, 
                          category.names= names(VENN.LIST), 
                          main="venn.diagram")
grid.draw(venn.plot)

x=VENN.LIST
names(x)
id=unique(unlist(x))
id
y=do.call(cbind,lapply(x, function(i){
  sign( id %in% i)
}))
rownames(y)=id
y=data.frame(y)
y$sum=rowSums(y)
y=y[order(y$sum,decreasing = T),]
head(y)

> head(y)
  g1 g2 g3 g4 sum
T  1  1  1  1   4
M  1  1  1  1   4
U  1  1  1  1   4
G  1  0  1  1   3
P  1  1  0  1   3
I  1  1  1  0   3

z=apply(y,1,function(x){paste(x[1:4],collapse = '-')})
as.data.frame(sort(table(z)))

> as.data.frame(sort(table(z)))
         z Freq
1  0-0-1-0    1
2  0-1-0-1    1
3  1-0-0-0    1
4  1-0-1-0    1
5  1-0-1-1    1
6  0-1-0-0    2
7  0-1-1-1    2
8  1-0-0-1    2
9  1-1-0-0    2
10 1-1-0-1    2
11 1-1-1-0    3
12 1-1-1-1    3
13 0-0-1-1    4
> which(z=='1-1-1-1')
T M U 
1 2 3 

library(UpSetR) 
p=upset(fromList(VENN.LIST), order.by = "freq")
p
p$New_data