如何用变量给定的半径绘制散点图？

Question

I'm pretty new to ggplot, I need to make a scatterplot with the size proportional to a variable of the df, so that some of the points get "zero radius" because a 0 value in the variable, but when I use the size aes, the points with 0 value are mapped to a non-zero radius point.

how can I get the desired effect?

Answer 1

According to the help, " scale_size_area ensures that a value of 0 is mapped to a size of 0". [Also worth noting, you can get a similar effect if you use scale_radius or scale_size and set the lower limit of the range argument to zero]. So we can do:

df <- data.frame(x=0:5, y=0:5, s=0:5)

ggplot(df, aes(x=x, y=y)) + 
  geom_point(aes(size=s)) +
  scale_size_area()    # NB scale_size(range = c(0, 6)) also works 

Note that this still shows the location of 'zero size' points using a single pixel. If you want them to be actually invisible, you can filter out the rows of zero size like this:

ggplot(df, aes(x=x, y=y, size=s)) + 
  geom_point(data = df[df$s != 0,]) +
  scale_size_area()