Help with legend

[Casault, Benoit]

I am trying to plot the data below such that the legend shows the red and black + markers along with the bubble scale.

Any help would be much appreciated.

 

df <- data.frame(x=seq(1,10), y=seq(1,10), z=c(1,0,5,3,1,8,0,12,1,0))

 

p <- ggplot() +

  geom_point(data = df %>% filter(z==0),

             aes(x=x, y=y),

             shape=3,

             size=5,

             colour="red",

             alpha=0.75,

             show.legend=T) +

  geom_point(data = df %>% filter(z>0 & z<=1),

             aes(x=x, y=y),

             shape=3,

             size=5,

             colour="black",

             alpha=0.75,

             show.legend=T) +

  geom_point(data = df %>% filter(z>1),

             aes(x=x, y=y, size=z),

             colour="red",

             alpha=0.75,

            show.legend=T)

 

Benoit Casault