Add geom_point for specific geom_area in ggplot2-CodePudding

With sample and code below, I'm trying to reproduce the effect of an image by adding geom_point for only type 3 data as shown in the end of this question:

library(data.table)
library(ggplot2)
df <- structure(list(date = c("2021-07-31", "2021-08-31", "2021-09-07", 
"2021-09-14", "2021-09-21", "2021-09-30", "2021-10-7", "2021-10-14", 
"2021-10-21", "2021-10-31", "2021-11-30", "2021-12-31", "2022-1-31", 
"2022-2-28"), value = c(190.3, 174.9, 163.2, 168.4, 168.6, 168.2, 
163.5, 161.6, 172.9, 166.5, 175.2, 197.7, 212.1, 177.9), type = c(1L, 
1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L)), class = "data.frame", row.names = c(NA, 
-14L))
df$type <- as.factor(df$type)
df$date <- as.Date(df$date)
setDT(df, key = "date")
types.extend <- c(1)
new.values <- df[, .SD[1], by = .(type)][, type := shift(type, type = "lag")][type %in% types.extend,]
# bind the new value to your original data
df <- rbind(df, new.values)
ggplot(data = df, 
       aes(x=date, y=value, group=type, color = type, fill = type))   
  geom_area(alpha=0.4, position = "identity")  
  geom_point(size=2)  
  scale_color_manual(values=c("1" = "gray", "2" = "red", "3" = "blue"), 
                     aesthetics = c("color", "fill"), name = "type")  
  theme_bw()

Out:

As I add geom_point(size=2) to the code, it add points for all data points, how could I add geom_point only for data's type is 3? Sincere thanks.

CodePudding user response：

You can use the data argument of geom_point to restrict the points being plotted. So replace your geom_point(size=2) call with geom_point(data=df[type==3], size=2)

(note this syntax only works because per the question df is a data.table, use df[df$type==3,] otherwise)

An alternative, if you didn't want the legend to include the points for the other two types would be to set the shape to NA for the types you didn't want to include:

 geom_point(size=2, aes(shape=type))  
  scale_shape_manual(values=c("1"=NA, "2"=NA, "3"=19))

CodePudding user response：

Not sure if I understood your question but try :

ggplot(data = df, 
       aes(x=date, y=value, group=type, color = type, fill = type))   
  geom_area(alpha=0.4, position = "identity")  
  geom_point(data = filter(df, type == 3), aes(x=date, y=value, group=type), size = 2)  
  scale_color_manual(values=c("1" = "gray", "2" = "red", "3" = "blue"), 
                     aesthetics = c("color", "fill"), name = "type")  
  theme_bw()

Out: