Adding points to stack line plot in ggplot

Question

I have a quick question on data visualization. I need to create a stacked line chart with points (geom_point) on the data point. I am able to create stacked chart with help of code below, but am having hard time figuring out how to add points to the data.

here are the content of test.csv:

Date    Category    Value
3/6/15      A       6.00
3/13/15     A       16.00
3/20/15     A       10.00
3/27/15     A       15.00
4/3/15      A       18.00
4/10/15     A       30.00
3/6/15      B       2
3/13/15     B       5.00
3/20/15     B       12.00
3/27/15     B       17.00
4/3/15      B       19.00
4/10/15     B       29.00
3/6/15      C       10
3/13/15     C       10
3/20/15     C       10
3/27/15     C       10
4/3/15      C       10
4/10/15     C       10

and here is my code:

df = read.csv("test.csv", header = T)
df$Date = as.Date(df$Date, format = "%m/%d/%y")
ggplot(df, aes(x = Date, y = Value, fill = Category)) + geom_area(colour="black", size=0.2, alpha=.4)

I tried adding geom_point(), but it does this.

I want these points on the stacked plot. Any help will be appreciated!

Thanks!

Answer 1

Use position_stack

ggplot(df, aes(x = Date, y = Value, fill = Category)) + 
  geom_area(colour="black", size=0.2, alpha=.4) +
  geom_point(position=position_stack())