Assigning values to the matrix by matching column names of matrix and character vectors

Question

I want to create a matrix and assign 1s based on matching the rownames of the matrix to the character vector.

## Here is the small example matrix
x <- as.character(c("rm78", "mn05", "hg78"))
y <- as.character(c("JU67", "EX56", "abcd", "rm78", "xyh56", "def", "terr6572"))
z <- as.character(c("abcd", "rh990", "mn05", "rm78", "xyh56", "efdg", "bett72"))

common <- Reduce(union, list(x,y,z))
dat.names <- c("x", "y", "z")
mat0 <- matrix(0, nrow = length(common), ncol = length(dat.names))
colnames(mat0) <- dat.names
rownames(mat0) <- common
mat0

If the character vectors x , y , and z matches the rownames of the matrix mat0 then assign 1 to the corresponding value in the matrix.

I am doing this individually for each vector and adding values to the matrix. I have a list of more than 12 such vectors and doing this way would be redundant. I think there may be a much efficient way of doing this.

for(i in rownames(mat0)[rownames(mat0) %in% x])
{
  # first column
  mat0[i , 1] <- 1 
}

for(i in rownames(mat0)[rownames(mat0) %in% y])
{
  # second column
  mat0[i , 2] <- 1 
}

for(i in rownames(mat0)[rownames(mat0) %in% z])
{
  # third column
  mat0[i , 3] <- 1 
}

Answer 1

Yes, you don't need multiple loops. In fact, you don't need any:

mat0[] <- do.call(cbind, lapply(list(x, y, z), function(i) +(rownames(mat0) %in% i)))
mat0
#>          x y z
#> rm78     1 1 1
#> mn05     1 0 1
#> hg78     1 0 0
#> JU67     0 1 0
#> EX56     0 1 0
#> abcd     0 1 1
#> xyh56    0 1 1
#> def      0 1 0
#> terr6572 0 1 0
#> rh990    0 0 1
#> efdg     0 0 1
#> bett72   0 0 1