Legend disappears when I fill the bars on ggplot2

Question

I'm trying to draw a multi layered pie chart using the following code

df <- data.frame(a = c(4, 3, 3, 8, 1, 1, 10),
                 b = c("x", "x", "x", "y", "y", "y", "z"),
                 c = c("x1", "x2", "x3", "y1", "y2", "y3", "z1"))

ggplot(df, aes(x = b, y = a, fill = c))+
  geom_bar(stat = "identity",
           color = "black", 
           fill = c("yellow","blue","black","green","red","white","black"))+
  coord_polar(theta="y")

The thing is, when I add the fill variable into the geom_bar I lose the legend, and can't add it at all, tried adding scale_fill_manual() as some suggested but it still doesn't work for me, any idea why this is happening?

PS: is it possible to remove the spaces between each bar/circle?

Answer 1

You don't need the second fill argument, the one in geom_bar .

library(ggplot2)
    df <- data.frame(a = c(4, 3, 3, 8, 1, 1, 10),
                     b = c("x", "x", "x", "y", "y", "y", "z"),
                     c = c("x1", "x2", "x3", "y1", "y2", "y3", "z1")
                     )

    ggplot(df, aes(x = b, y = a, fill = c))+
      geom_bar(stat = "identity",
               width=1,#set width to remove white space, b/c the default is 0.9
               color = "black",)+
      coord_polar(theta="y")+ #Note you don't need the scale_fill_manual below; if omitted, r uses the default palette
      scale_fill_manual(values = c("yellow","blue","black","green","red","white","black"))

    )

Result: