geom_text() & color gradient

Question

I am looking to set a color gradient from green for low and red for high on the geom_text function. My code is as follows:

mydata <-  data.frame(R_Test_Data)

datatime <- mydata$TIMESTAMP
wind_speed <- mydata$WS_ms_Avg
wind_direction <-mydata$WS_ms_WVc

ggplot(data = mydata, aes(x = datatime, y = wind_speed))+
  geom_line() +
  geom_text(aes(angle=-wind_direction + 270), label="→", 
            colour = wind_speed, size = 7 ) +
 scale_colour_gradient(low="green", high="red") 

I am looking for something kind of like this:

Answer 1

Map colour to to a numeric variable - e.g. this maps color to y by specifying color=y within aes:

set.seed(1);df <- data.frame(x = 1:10, y = 1:10, angle = runif(10,90,180))
library(ggplot2)
ggplot(df, aes(x,y)) + 
  geom_text(aes(angle=angle, color=y), label="-", size = 12) + 
  scale_colour_distiller(palette="RdYlGn")