Menu
I am using scale_colour_manual to specify the possible keys in the legend. However, if I use stat_function to plot custom function, the legend is missing.
Any ideas why this happen?
library(ggplot2) MyFun <- function(x, p) { res <- x^(1 / p) return(res) } my.df <-data.frame(x = c(0,1)) plt <- ggplot(my.df, aes(x=x)) + stat_function(fun = MyFun, n = 1000, args = list(p = 10), colour = "red") + stat_function(fun = MyFun, n = 1000, args = list(p = 3), colour = "blue") + stat_function(fun = MyFun, n = 1000, args = list(p = 2), colour = "green") + stat_function(fun = MyFun, n = 1000, args = list(p = 1), colour = "orange") + scale_colour_manual(values = c("red", "blue", "green", "orange")) print(plt) 
434
stat_function() computes the following variables: x. x values along a grid. y.
Geoms. A layer combines data, aesthetic mapping, a geom (geometric object), a stat (statistical transformation), and a position adjustment. Typically, you will create layers using a geom_ function, overriding the default position and stat if needed.
In order to create a normal curve, we create a ggplot base layer that has an x-axis range from -4 to 4 (or whatever range you want!), and assign the x-value aesthetic to this range ( aes(x = x) ). We then add the stat_function option and add dnorm to the function argument to make it a normal curve.
Plotting a function is very easy with curve function but we can do it with ggplot2 as well. Since ggplot2 provides a better-looking plot, it is common to use it for plotting instead of other plotting functions. To plot a function, we should specify the function under stat_function in ggplot.
Put colour= inside the aes() and then provide name for particular line as is should appear in legend. Legend is made for aesthetics that are only inside aes() call.
ggplot(my.df, aes(x=x)) + stat_function(fun = MyFun, n = 1000, args = list(p = 10), aes(colour = "line1")) + stat_function(fun = MyFun, n = 1000, args = list(p = 3), aes(colour = "line2")) + stat_function(fun = MyFun, n = 1000, args = list(p = 2), aes(colour = "line3")) + stat_function(fun = MyFun, n = 1000, args = list(p = 1), aes(colour = "line4")) + scale_colour_manual("Lgend title", values = c("red", "blue", "green", "orange")) 
77
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
