[英]R which samples were drawn randomly from matrix?
I am trying to determine which columns were sampled from a matrix randomly sampled within each row. 我试图确定哪些列是从每一行中随机抽样的矩阵中抽样的。 The function sample does not appear to have the ability to tell you which locations were actually sampled.
函数样本似乎没有能力告诉您实际采样的位置。 Now, a simple matching routine can solve the problem if all values are unique.
现在,如果所有值都是唯一的,那么简单的匹配例程就可以解决问题。 However, they are not in my case, so this will not work.
但是,就我而言,它们不是,所以这行不通。
x <- c(2,3,5,1,6,7,2,3,5,6,3,5)
y <- matrix(x,ncol=4,nrow=3)
random <- t(apply(y,1,sample,2,replace=FALSE))
y ÿ
[,1] [,2] [,3] [,4]
[1,] 2 1 2 6
[2,] 3 6 3 3
[3,] 5 7 5 5
random 随机
[,1] [,2]
[1,] 2 6
[2,] 3 3
[3,] 5 5
With repeated values in the original matrix, I cannot tell if random[1,1] was sampled from column 1 or column 3, since they both have a value of 2. Hence, matching won't work here. 对于原始矩阵中的重复值,我无法确定是否从第1列或第3列中采样了random [1,1],因为它们的值均为2。因此,匹配在这里不起作用。
Accompanying the matrix "random" I would also like a matrix that gives the column from which each value was sampled, in an identically sized matrix. 伴随矩阵“随机”,我还想要一个矩阵,该矩阵以大小相同的矩阵给出从中采样每个值的列。 For example, such as:
例如,例如:
[,1] [,2]
[1,] 1 4
[2,] 1 3
[3,] 3 4
Thanks! 谢谢!
You need to save your random selections from sample
separately so you don't have to worry about matching later. 您需要分别保存
sample
的随机选择,因此您不必担心以后进行匹配。 Eg, using y
again: 例如,再次使用
y
:
y
# [,1] [,2] [,3] [,4]
#[1,] 2 1 2 6
#[2,] 3 6 3 3
#[3,] 5 7 5 5
set.seed(42)
randkey <- t(replicate(nrow(y),sample(1:ncol(y),2)))
# [,1] [,2]
#[1,] 4 3
#[2,] 2 3
#[3,] 3 2
random <- matrix(y[cbind(c(row(randkey)), c(randkey))], nrow(y))
# [,1] [,2]
#[1,] 6 2
#[2,] 6 3
#[3,] 5 7
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