ggplot2 change colours how

Question

I want to do a ggplot2 scatter plot

    scores <- data.frame( SampleID = rep(LETTERS[1:3], 5), PC1 = rnorm(15), PC2 = rnorm(15) )
library( ggplot2 )
ggpl         


        

Answer 1

scale_color_manual let's you pick the colors used.

ggplot( scores, aes( x = PC1, y = PC2, colour = SampleID ) ) +
    geom_point() +
    scale_color_manual(values = c("red", "black", "dodgerblue2"))

The cyl in the example refers to the cyl column of the mtcars dataset used in the example. If you would rather use shapes then colors, don't use the colour aesthetic, use the shape aesthetic instead.

ggplot( scores, aes( x = PC1, y = PC2, shape = SampleID ) ) +
    geom_point()

If you want to choose shapes (using usual R pch codes), then use scale_shape_manual.