I want to plot a line graph, with multiple lines, coloured depending on a grouping variable. Now I want to set the legend labels via scale
-command:
scale_color_manual(values = colors_values, labels = ...)
The legend labels are as following: "x^2", "x^3", "x^4" etc., where the range is dynamically created. I would now like to dynamically create the expression as label text, i.e.
"x^2"
should become x2"x^3"
should become x3
etc.
The amount of legend labels varies, so I thought about something like as.expression(sprintf("x^%i", number))
, which does of course not work as label
parameter for the scale
function.
I have searched google and stack overflow, however, I haven't found a working solution yet, so I hope someone can help me here.
Here's a reproducible example:
poly.term <- runif(100, 1, 60)
resp <- rnorm(100, 40, 5)
poly.degree <- 2:4
geom.colors <- scales::brewer_pal(palette = "Set1")(length(poly.degree))
plot.df <- data.frame()
for (i in poly.degree) {
mydat <- na.omit(data.frame(x = poly.term, y = resp))
fit <- lm(mydat$y ~ poly(mydat$x, i, raw = TRUE))
plot.df <- rbind(plot.df, cbind(mydat, predict(fit), sprintf("x^%i", i)))
}
colnames(plot.df) <- c("x","y", "pred", "grp")
ggplot(plot.df, aes(x, y, colour = grp)) +
stat_smooth(method = "loess", se = F) +
geom_line(aes(y = pred))
scale_color_manual(values = geom.colors
# here I want to change legend labels
# lables = expresion???
)
I would like to have the legend labels to be x2, x3 and x4.
It's important to ensure correct mapping if you change values or labels in the scale. Thus, you should always use named vectors.