lower.tri {base}

R Documentation

Lower and Upper Triangular Part of a Matrix

Description

Returns a matrix of logicals the same size of a given matrix with entries TRUE in the lower or upper triangle.

Usage

lower.tri(x, diag = FALSE)
upper.tri(x, diag = FALSE)

Arguments

x	a matrix.
diag	logical. Should the diagonal be included?

See Also

diag, matrix.

Examples

m2 <- ma <- matrix(1:20, 4, 5)
m2[lower.tri(m2)] <- NA
m2
stopifnot(lower.tri(ma) == !upper.tri(ma, diag=TRUE))

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