r - 如何创建一个列表，使列表中的每个元素都是基于 R 中矩阵的数据框的行名称

Question

我有一个示例数据帧 s1

s1=data.frame(c1=c("red","green","blue","yellow","orange","black","white"),col1=c("car1","car2","car3","car4","car5","car6","car7"))
s1=s1 %>% remove_rownames %>% column_to_rownames(var="c1")

只有一列-col1，行名称为红色、绿色、蓝色等。

       col1
red    car1
green  car2
blue   car3
yellow car4
orange car5
black  car6
white  car7

我还有一个只包含 1 和 0 的矩阵

m1= matrix(c(1,0,0,1,0),nrow =7, ncol =3, byrow = TRUE) 

     [,1] [,2] [,3]
[1,]    1    0    0
[2,]    1    0    1
[3,]    0    0    1
[4,]    0    1    0
[5,]    0    1    0
[6,]    1    0    0
[7,]    1    0    1

我想创建一个列表，使得列表中的每个元素都包含 s1 的行名称，前提是矩阵的相应元素为 1。我需要对矩阵的所有列进行迭代。

输出应该看起来像这样

l1=list(c("red","green","black","white"),c("yellow","orange"),c("green","blue","white"))

我尝试使用此代码，但无法将其应用到每一列

row.names(s1)[which(m1[,1]==1)]

请注意，实际的数据帧和矩阵都要大得多。谢谢!

Answer 1

在逻辑矩阵上使用 asplit 按“m1”的列进行拆分，并使用索引对“s1”的行名进行子集化

lapply(asplit(m1 == 1, 2), function(x) row.names(s1)[x])

-输出

[[1]]
[1] "red"   "green" "black" "white"

[[2]]
[1] "yellow" "orange"

[[3]]
[1] "green" "blue"  "white"

---

或者使用 apply 和 MARGIN=2 来循环遍历列和子集

apply(m1==1, 2, function(x) row.names(s1)[x])