CODEWITHSUNDEEP
rmatrix
user8389133
user8389133

Reputation:

How to generate a matrix based on a values of another matrix in R

Suppose that I have lower triangular matrix i.e.,

w1 <- c(0,0.6,0.3,0.6,0.7,
    0,0,0.6,0.6,0.7,
    0,0,0,0.6,0.6,
    0,0,0,0,0.7,
    0,0,0,0,0)
w1 <- matrix(w1,5,5)

Then, I would like the second matrix to be a lower triangular matrix, say w2 where each non-zero values of w2 are 1-the corresponding values of w1.

Like this:

w2 <- c(0,0.4,0.7,0.4,0.3,
    0,0,0.4,0.4,0.3,
    0,0,0,0.4,0.4,
    0,0,0,0,0.3,
    0,0,0,0,0)
w2 <- matrix(w2,5,5) 
w <- list(w1, w2)

How can I get w2 automatically?

Upvotes: 0

Views: 65

Answers (2)

jogo
jogo

Reputation: 12559

You can use the indexing of lower.tri() also on the left side:

w2new <- matrix(0, dim(w1)[1], dim(w1)[2])
w2new[lower.tri(w2new)] <- 1 - w1[lower.tri(w1)]

Upvotes: 1

alan ocallaghan
alan ocallaghan

Reputation: 3038

Since most operations in R are vectorised, you can simply use ifelse to either subtract 1 - w1, or if w1 is zero, retain zero.

ifelse(w1 == 0, 0, 1 - w1)

Upvotes: 1

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