Issue
I am trying to make a parabola in R to layer on top of my ggplot with the function
y = -(10x-8)^2 + 113
using the code
eqn = function(x) {-(10*x - 8)^2 + 113}
But when I add it to the ggplot using
+ stat_function(fun = eqn) + xlim(115, 0)
It’s max is 0, when it should be 113, and if I just remove the 113 nothing changes, so I just do not understand why it does not recognize the "+113" at the end there.
Solution
You can get the values of a ggplot using layer_data:
eqn = function(x) {-(10*x - 8)^2 + 113 }
library(ggplot2)
layer_data(ggplot() + stat_function(fun = eqn) + xlim(115, 0))
...
99 -2.30 -112.00 1 -1 black 0.5 1 NA
100 -1.15 100.75 1 -1 black 0.5 1 NA
101 0.00 49.00 1 -1 black 0.5 1 NA
the last value is 49 which is exactly 113 - 8^2 :
eqn(0)
[1] 49
Perhaps you forgot to source again eqn function after adding 113.
Answered By – Waldi
Answer Checked By – David Goodson (BugsFixing Volunteer)