sorting a complex vector by imaginary part in R

Question

roots <- polyroot(c(5, 4, 3, 2, 1))

I want to sort the roots by ascending order of the imaginary part. By default the sort function sor

Answer 1

Use Im function to extract the imaginary part and sort it.

roots <- polyroot(c(5, 4, 3, 2, 1))
#[1]  0.287815+1.416093i -1.287815+0.857897i -1.287815-0.857897i
#[4]  0.287815-1.416093i

roots[order(Im(roots))]
#[1]  0.287815-1.416093i -1.287815-0.857897i -1.287815+0.857897i
#[4]  0.287815+1.416093i