In the plot, smaller bubbles will be hidden by bigger bubbles. if I use alpha, they will appear. I would like that small bubbles superpose the bigger ones without using alpha

   library(ggplot2)
   library(dplyr)

The dataset is provided in the gapminder library

    library(gapminder)
    data <- gapminder %>% filter(year=="2007") %>% dplyr::select(-year)

    # Most basic bubble plot
   data %>%
  arrange(desc(pop)) %>%
  mutate(country = factor(country, country)) %>%
 ggplot(aes(x=gdpPercap, y=lifeExp, size=pop, color=continent))  
geom_point(alpha=0.5)  
scale_size(range = c(.1, 24), name="Population (M)")

CodePudding user response：

The small points are already plotted over the large points. What you need is an outline on the points. You can do this by selecting shape = 21 and using the fill aesthetic for their overall color. Their outline can be whatever color you like, though here I have made them a darker version of the fill color, which gives a more subtle outline:

library(ggplot2)
library(dplyr)
library(gapminder)
library(colorspace)

data <- gapminder %>% filter(year=="2007") %>% dplyr::select(-year)

data %>%
  arrange(desc(pop)) %>%
  mutate(country = factor(country, country)) %>%
  ggplot(aes(gdpPercap, lifeExp, size = pop, fill = continent,
             color = after_scale(darken(fill, 0.3))))  
  geom_point(shape = 21)  
  scale_size(range = c(.1, 24), name = "Population (M)")  
  scale_x_continuous("GDP per Capita", labels = scales::dollar)  
  ylab("Life Expectancy")  
  theme_minimal(base_size = 20)  
  scale_fill_brewer(palette = "Pastel1")  
  ggtitle("Average life expectancy 2007")  
  guides(size = "none",
         fill = guide_legend(override.aes = list(size = 6)))  
  theme(panel.background = element_rect(fill = "gray95", color = NA),
        legend.title = element_text(size = 25, face = 2),
        legend.text = element_text(size = 25, face = 2))

CodePudding user response：

Here is another version of @Allan Cameron's solution:

# Libraries
library(ggplot2)
library(dplyr)
library(viridis)
library(gapminder)

gapminder %>% 
  filter(year=="2007") %>%
  select(-year) %>% 
  arrange(desc(pop)) %>%
  mutate(country = factor(country, country)) %>%
  ggplot(aes(x=gdpPercap, y=lifeExp, size=pop, fill=continent))  
  geom_point(alpha=0.5, shape=21, color="black")  
  scale_size(range = c(.1, 24), name="Population (M)", guide="none") 
  scale_fill_viridis(discrete=TRUE, option="A")  
  theme_bw()  
  theme(legend.position="bottom")  
  ylab("Life Expectancy")  
  xlab("Gdp per Capita")