R: ggplot better gradient color

Question

I am using ggplot to plot Proportional Stacked Bar plot. And the Plot I am getting is something like this:

Answer 1

I'd use scale_fill_manual=c("red","green"), you can put more colors if you want or scale_fill_brewer(palette="Reds"), I like this one. You can use palettes here

Answer 2

Thanks @zelite and @SimonO101 for your help. This is simpler version of what both of you proposed. Adding here for the completeness.

library(ggplot2)
library(reshape2)
library(RColorBrewer)

getColors<-function(n){
   mypal<-colorRampPalette(brewer.pal(12, "Paired"))
   sample(mypal(n), n, replace=FALSE)
}

PropBarPlot<-function(df, mytitle=""){
   melteddf<-melt(df, id=names(df)[1], na.rm=T)
   n<-length(levels(factor(melteddf$variable)))

   ggplot(melteddf, aes_string(x=names(df)[1], y="value", fill="variable")) + 
      geom_bar(position="fill") + 
      scale_fill_manual(values=getColors(n)) + 
      theme(axis.text.x = element_text(angle=90, vjust=1)) + 
      labs(title=mytitle)
}

df <- data.frame(id=letters[1:3],
             val0=1:3,
             val1=4:6,
             val2=7:9, 
             val3=2:4, 
             val4=1:3, 
             val5=4:6, 
             val6=10:12, 
             val7=12:14)

print(PropBarPlot(df))

Thanks.

Answer 3

Borrowing some code from @SimonO101

library(ggplot2)
library(reshape2)
library(RColorBrewer)
mypal <- colorRampPalette( brewer.pal( 9 , "Set1" ) ) #you can try using different palete instead
#of "Set1" until it looks good to you

intercalate <- function(n){ #my crude attempt to shuffle the colors
  c(rbind(1:(n/2), n:(n/2+1))) #it will only work for even numbers
}

PropBarPlot<-function(df, mytitle=""){
  melteddf<-melt(df, id=names(df)[1], na.rm=T)
  ggplot(melteddf, aes_string(x=names(df)[1], y="value", fill="variable")) + 
    geom_bar(position="fill") + 
    theme(axis.text.x = element_text(angle=90, vjust=1)) + 
    labs(title=mytitle)+
    scale_fill_manual( values = mypal(8)[intercalate(8)] )
  #better would be to calculate the different number of categories
  #you have and put that instead of the number 8
}

df <- data.frame(id=letters[1:3],
                 val0=1:3,
                 val1=4:6,
                 val2=7:9, 
                 val3=2:4, 
                 val4=1:3, 
                 val5=4:6, 
                 val6=10:12, 
                 val7=12:14)

print(PropBarPlot(df))

See if that works better for your needs.

Answer 4

How about using scale_fill_brewer which makes use of colour palettes from the ColorBrewer website, implemented by the package RColorBrewer?

ggplot(diamonds, aes(clarity, fill=cut) ) +
geom_bar( ) +
scale_fill_brewer( type = "div" , palette = "RdBu" )

There are a number of different diverging palettes you can choose from.

require(RColorBrewer)
?brewer.pal

If you need more colours you can use the colorRampPalette features to interpolate between some colours (and I would use a brewer.pal palette for this). You can do this like so:

# Create a function to interpolate between some colours
mypal <- colorRampPalette( brewer.pal( 6 , "RdBu" ) )
# Run function asking for 19 colours
mypal(19)
 [1] "#B2182B" "#C2373A" "#D35749" "#E47658" "#F0936D" "#F4A989" "#F8BFA5"
 [8] "#FCD6C1" "#F3DDD0" "#E7E0DB" "#DAE2E6" "#CBE1EE" "#ADD1E5" "#90C0DB"
 [15] "#72AFD2" "#5B9DC9" "#478BBF" "#3478B5" "#2166AC"

In your example which requires 8 colours you an use it like this with scale_fill_manual():

PropBarPlot<-function(df, mytitle=""){
   melteddf<-melt(df, id=names(df)[1], na.rm=T)
   ggplot(melteddf, aes_string(x=names(df)[1], y="value", fill="variable")) + 
     geom_bar(position="fill") + 
     theme(axis.text.x = element_text(angle=90, vjust=1)) + 
     labs(title=mytitle)+
    scale_fill_manual( values = mypal(8) )
}

print(PropBarPlot(df))