ggplot2: barplot with colors as a function of y-axis value

bar-chart, ggplot2, r

Solution

You're basically there with your current code. Just add the scale_fill_gradient function.

bar <- ggplot(data = df, aes(x = factor(dat, levels = month.abb), y = val, 
              fill=val)) +
       geom_bar(stat = 'identity') + 
       scale_fill_gradient2(low=LtoM(100), mid='snow3', 
       high=MtoH(100), space='Lab')

However, allowing scale_fill_gradient2 to take care of the gradient-ing works pretty well

bar <- ggplot(data = df, aes(x = factor(dat, levels = month.abb), y = val, 
              fill=val)) + 
       geom_bar(stat = 'identity') + 
       scale_fill_gradient2(low='red', mid='snow3', high='darkgreen', space='Lab')

Problem

I have this simple code (data + barplot) : ``` dat <- c('Jan','Feb','Mar', 'Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec') val <- c(-2.5, 3, 2.5, -3.3, -1, 0.2, 6, 4.3, 5.5, 2, -1.9, -2.3) df <- data.frame(dat, val) bar <- ggplot(data = df, aes(x = factor(dat, levels = month.abb), y = val)) + geom_bar(stat = 'identity') print(bar) ``` Elsewhere I created a heatmap using the following palette: ``` # Palette LtoM <-colorRampPalette(c('red', 'yellow' )) Mid <- "snow3" MtoH <-colorRampPalette(c('lightgreen', 'darkgreen')) ``` that is called by: ``` scale_fill_gradient2(low = LtoM(100), mid = Mid, high = MtoH(100)) ``` Now I would like to use a similar color palette for my barplot, that is I would like the color in each bar to be a function of the height (some grade from red for mimimum y to green for maximum y). How can I do that, please?

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