Check if vector in a matrix

问题

I have a matrix

new<-matrix(9,4,4)
new[1,1]<-0

v1<-c(0,0)

new thus looks like this:

I now want to check if this matrix contains the vector v1. So I did

v1 %in% new

and obtain TRUE TRUE although I would like to check the whole vector of two zeros in a row/ column and thus would like to get a FALSE.

回答1:

You can use rollapply from zoo to test if matrix contains a vector:

library(zoo)
any(apply(new, 2, rollapply, length(v1), identical, v1))
#[1] FALSE

new[2,1] <- 0
any(apply(new, 2, rollapply, length(v1), identical, v1))
#[1] TRUE

回答2:

You can use a combination of isTRUE and all.equal, while intersect the vector with the matrix i.e.

isTRUE(all.equal(v1, intersect(v1, new)))
#[1] FALSE

v2 <- c(0, 9)
all.equal(v2, intersect(v2, new))
#[1] TRUE

回答3:

Is this what you want?

The vector has two values, so if you want to check whether it is contained in the matrix you will have to paste the two values together to obtain 0,0:

paste0(v1, collapse = ",") %in% new
[1] FALSE

or this, which compares the string 0,0 from the pasted-together vector to the pasted-together rows of the matrix:

paste0(v1, collapse = ",") %in% apply(new, 2, paste0, collapse = ",")
[1] FALSE

or this, which searches for 0,0 in the corresponding pairs of two digts separated by comma in the pasted-together rows of the matrix:

library(stringr)
paste0(v1, collapse = ",") %in% unlist(str_split(apply(new, 2, paste0, collapse = ","), "(?<=\\d,\\d),(?=\\d,\\d)"))

This latter solution seems the most likely as it searches for 0,0 %in% this vector, which is the output of unlist(str_split(apply(new, 2, paste0, collapse = ","), "(?<=\\d,\\d),(?=\\d,\\d)")):

[1] "0,9" "9,9" "9,9" "9,9" "9,9" "9,9" "9,9" "9,9"

来源：https://stackoverflow.com/questions/62693039/check-if-vector-in-a-matrix

标签

matrix