Sort legend in ggplot2

Question

I have produced a stacked percent barplot from the following data, which is in a csv file,

,ONE,TWO,THREE 1,2432,420,18 2,276,405,56 3,119,189,110 4,90,163,140 5,206,280,200 6,1389,1080,1075 7,3983,3258,4878 8,7123,15828,28111 9,8608,48721,52576 10,9639,44725,55951 11,8323,45695,32166 12,2496,18254,26600 13,1524,8591,18583 14,7861,1857,1680 15,10269,5165,4618 16,13560,64636,63262 

using the following code

library(ggplot2) library(reshape2) library(scales)  data <- read.csv(file="file.csv",sep=",",header=TRUE) data <- data[,2:ncol(data)] datam <- melt(cbind(data,ind = sort(rownames(data))),is.var = c('ind')) datam$ind <- as.numeric(datam$ind) ggplot(datam,aes(x = variable, y = value,fill = factor(as.numeric(ind)))) + geom_bar(position = "fill") + scale_y_continuous(labels =percent_format()) + scale_fill_discrete("Barcode\nMatch")  +xlab("Barcode")+ylab("Reads") 

The result is

The problem is that the items in the legend are not in the same order as the stacks they represent. The colours and the numbers are right but the order is not. In other words, is there a way to invert the order of the items in the legend? Thanks

Answer 1

you can use a new option reverse = TRUE:

ggplot(datam,aes(x = variable, y = value,fill = factor(as.numeric(ind)))) +   geom_bar(position = "fill") + scale_y_continuous(labels =percent_format()) +   scale_fill_discrete("Barcode\nMatch") + xlab("Barcode")+ylab("Reads") +   guides(fill = guide_legend(reverse = TRUE)) 

Answer 2

Add + scale_fill_hue(breaks=c("new order 1","new order 2","new order...")) as in:

library(ggplot2) ggplot(data=PlantGrowth, aes(x=group, fill=group)) + geom_bar() +      geom_bar(colour="black", legend=FALSE) +      scale_fill_hue(breaks=c("trt1","ctrl","trt2")) 

I'd also check out http://wiki.stdout.org/rcookbook/Graphs/Legends%20(ggplot2)/ for more.

This may have changed and become easier with he new ggplot but I'm not sure.