Modifying select off-diagonal items in a matrix
This is something I have had the occasion to do, and never remember how, so this is legitimately a reminder to my future self of how to do things with off-diagonal elements of a matrix.
Select rows and columns are easy: mat[1:10, ] or mat[, -c(5)], for example, as is the diagonal: diag(mat) <- 0.
However, access to select off-diagonal slices is not obvious, without a loop. Fortunately, some friendly experts at Stack Overflow provide an excellent solution, which I include below with an invented application.
To leave a comment
for the author, please follow the link and comment on their blog: is.R()
offers daily e-mail updates
news and tutorials
on topics such as: Data science
, Big Data, R jobs
, visualization (ggplot2
), programming (RStudio
, Web Scraping
) statistics (regression
, time series
) and more...
If you got this far, why not subscribe for updates
from the site? Choose your flavor: e-mail
, or facebook