Question

我有一个矩阵：

a<-replicate(3,sample(c(0,1),4, replace=T))

和矢量：

b<-c(0,1,0)

我想在a中找出与向量b对应的行号。

查看a==b我可以看到每个条件返回TRUE的行，但是如何获取行号？

Answer 1

set.seed(42)
a < -replicate(3, sample(c(0, 1), 4, replace=T))
#     [,1] [,2] [,3]
#[1,]    1    1    1
#[2,]    1    1    1
#[3,]    0    1    0
#[4,]    1    0    1


b <- c(0, 1, 0)

#vector recycling is done in row direction --> transpose the matrix
#logical values get coerced to integers in colSums   
which(colSums(t(a) == b) == 3L)
#[1] 3

Answer 2

set.seed(1)
a <- replicate(3,sample(c(0,1),4, replace=T))
b<-c(0,1,0)
which(apply(a, 1, FUN=function(x) all(x == b)))
# [1] 2

Answer 3

set.seed(15)
a <- replicate(5,sample(c(0,3),6, replace=T))
b<-c(0,1,0)
which(apply(a, 1, FUN=function(x) all(x == b)))

识别所有值与矢量匹配的行号

3 个答案: