Hello, I am drawing contour lines for a function of 2 variables at one level of the value of the function and want to include a small arrow in any direction of increase of the function. Is there some way to do that?
Below is an example that creates the contour lines. How do I add one small arrow on each line in the direction of increase of the function (at some central point of the contour line)? Any direction will do, but perhaps the direction of the gradient will be the best. Thanks in advance. DB -------------------------------------------- library(tidyverse) x <- seq(1,2,length.out=100) y <- seq(1,2,length.out=100) myf <- function(x,y) {x*y} myg <- function(x,y) {x^2 + y^2} d1 <- expand.grid(X1 = x, X2 = y) %>% mutate(Z = myf(X1,X2)) %>% as.data.frame() d2 <- expand.grid(X1 = x, X2 = y) %>% mutate(Z = myg(X1,X2)) %>% as.data.frame() ggplot(data = d1, aes(x=X1,y=X2,z=Z))+ stat_contour(breaks = c(2)) + stat_contour(data=d2, aes(x=X1,y=X2,z=Z), breaks=c(6)) [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.