Create a Diagonal Label Comparison Matrix (Element-wise)

Compares labels at corresponding positions (element-wise) between two equal-length vectors `a` and `b`. Creates a sparse matrix with entries only on the diagonal, where position (i, i) is 1 if `a[i]` and `b[i]` satisfy the comparison.

Usage

diagonal_label_matrix(
  a,
  b,
  type = c("s", "d"),
  dim1 = length(a),
  dim2 = length(b)
)

Arguments

a

A vector of labels for the first set of data points.

b

A vector of labels for the second set of data points. Must have same length as `a`.

type

A character specifying the comparison type: "s" for same labels (a[i] == b[i]) or "d" for different labels (a[i] != b[i]). Default is "s".

dim1

The row dimension of the output matrix (default: length(a)).

dim2

The column dimension of the output matrix (default: length(b)).

Value

A sparse diagonal matrix where entry (i, i) is 1 if the labels at position i satisfy the comparison, 0 otherwise.

Details

This function performs element-wise comparison, NOT all-pairs comparison. For all-pairs comparison (block structure), use binary_label_matrix.

The vectors `a` and `b` must have the same length. If they differ, recycling will occur which is likely unintended.

See also

binary_label_matrix for all-pairs comparison

Examples

a <- factor(c("x","y","x"))
b <- factor(c("x","x","y"))
diagonal_label_matrix(a, b, type="d")
#> 3 x 3 sparse Matrix of class "dgCMatrix"
#>           
#> [1,] . . .
#> [2,] . 1 .
#> [3,] . . 1