filled / open circle by group

Question

I have trouble making a filled / open circle plot by group.

My data looks like:

Body_weight  Gender

50            M

60            M 

55            M

45            F

43            F

42            F

I want to plot the male weights in filled circle and the female weights in open.

I tried:

ggplot(data, aes(x=Gender, y=Body_weight))+

 geom_point(aes(fill=Gender))

But, this only gives filled circles for both gender.
I have no idea why this does not work.

geom_point(aes(shape=Gender))

works and gives a circle / triangle plot.

Answer 1

The aesthetic "fill" does not determine if the point is filled with colour or not, but fills it with a different colour for each gender. The way to do what you want is using "shape" and mapping the shapes to open and closed circle instead of the default circle/triangle you get. To do this you need to use scale_shape_manual.

ggplot(data, aes(x=Gender, y=Body_weight)) + 
    geom_point(aes(shape=Gender)) +
    scale_shape_manual(values = c(16, 21))

Have a look at http://sape.inf.usi.ch/quick-reference/ggplot2/shape for other shapes available