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rfunctionggplot2stat

Does ggplot use dynamic function for statistic functions?

So I'm running an optimization problem and am trying to add the function at each point in time to a plot. I'm able to plot the function but I have the variables stored and it seems like r doesn't evaluate the function until it renders it. It's hard to explain, but I have a simple example that shows it. 

data = data.frame(x = runif(20, -10, 10), y = runif(20, -10,10))
p <- ggplot(data, aes(x = x, y =y))
slope = 0.5
yoff = 1
p <- p + stat_function(fun = function(x) slope*x+yoff)
slope = 1
yoff = -1
p <- p + stat_function(fun = function(x) slope*x+yoff)
p

And what I want is two lines on the graph with the slope and y-intercept that I had when I added the function to the graph.

Solution

  • If you have a lot of them, make a list of functions:

    make_fun <- function(slope,yoff) {slope; yoff; function(x) x*slope + yoff}
> l <- mapply(FUN = make_fun,slope = 1:2,yoff = 3:4)
> l[[1]](1)
[1] 4
> l[[2]](1)
[1] 6