How to fill geom_area () graph with ggplot?

Question

I have a geom_area graph that looks like this:

I want to color everything above the x axis and everything under the red x axis. I have a category column in my data that contains the row “positive” for all positive values ​​and “negative” for all negative values, so I tried just doing fill = category and using scale_fill_manual to set positive to green and negative to red. but this gives me the following:

Green above x looks correct, but red below the axis is incorrect. I checked my data and there are no negative data points where it dyes red after October 20th and use geom_point instead, I get the correct colors.

Here is an example of my data:

created score category 2011-10-19 21:26:19 2 positive 2011-10-19 22:50:33 -2 negative 2011-10-20 15:12:38 -2 negative 2011-10-20 17:19:24 -2 negative 2011-10-20 22:12:44 2 positive 2011-10-20 22:16:57 4 positive 2011-10-21 08:22:53 2 positive 

and here is the code that I use to make the plot:

ggplot(data = df, aes(x = created, y = score, colour = category)) + geom_point(aes(fill = category)) + scale_fill_manual(values = c("positive" = "green", "negative" = "red"))

My problem might be related to this previous question .

Answer 1

You need to create a new grouping variable for each positive / negative segment. To make the transition less "blocky", you can simply interpolate the data first:

 require(ggplot2) # Load data df = read.table('data.txt', header=T) df$created = as.POSIXct(df$created, tz='UTC') # Interpolate data lin_interp = function(x, y, length.out=100) { approx(x, y, xout=seq(min(x), max(x), length.out=length.out))$y } created.interp = lin_interp(df$created, df$created) created.interp = as.POSIXct(created.interp, origin='1970-01-01', tz='UTC') score.interp = lin_interp(df$created, df$score) df.interp = data.frame(created=created.interp, score=score.interp) # Make a grouping variable for each pos/neg segment cat.rle = rle(df.interp$score < 0) df.interp$group = rep.int(1:length(cat.rle$lengths), times=cat.rle$lengths) # Plot dev.new(width=6, height=4) ggplot(data = df.interp, aes(x = created, y = score, fill=score>0, group=group)) + geom_area() + scale_fill_manual(values = c('green', 'red'))