CODEWITHSUNDEEP
rggplot2pie-chart
Areza
Areza

Reputation: 6080

Coloring slices of a pie bar as gradient in ggplot2

Imagine I have a pie bar in ggplot2, 

data <- data.frame(cluster = paste("Cluster", 1:3), size = c(0.33, 0.33, 0.33))
data = rbind(data, data)

ggplot(data, aes(x = factor(1), fill = cluster, weight=size)) + 
  geom_bar(width = 1) + coord_polar(theta="y")+ theme_bw() + 
  scale_x_discrete("",breaks=NULL) + scale_y_continuous("",breaks=NULL) +
  theme(panel.border=element_blank(), 
        strip.text=element_blank(), 
        strip.background=element_blank(), 
        legend.position="none", 
        panel.grid=element_blank())

There is another vector of strength that I is represented by a vector (0.2, -1, 1). I like to color each slices as a gradient from blue to red. say, blue, for -1, and and red for 1.

Upvotes: 0

Views: 776

Answers (1)

dlaehnemann
dlaehnemann

Reputation: 701

First of all, I would suggest a clearer data frame which contains all the data at once, created as follows:

> data <- data.frame(cluster = paste("Cluster", 1:3), size = c(0.2, 0.3, 0.5), strength = c(0.2, -1, 1))
> data
    cluster size strength
1 Cluster 1  0.2      0.2
2 Cluster 2  0.3     -1.0
3 Cluster 3  0.5      1.0

And then the following minimal code produces a pie chart with the fill colour diverging on a scale around midpoint zero depending on the cluster's strength value:

> ggplot(data, aes( x = factor(1), group = cluster, fill = strength, weight = size)) + geom_bar(width = 1) + coord_polar( theta = "y") + scale_fill_gradient2()

For reference, have a look at the scale_fill_gradient2 doc page examples in the geom_bar doc page: http://docs.ggplot2.org/current/scale_gradient2.html http://docs.ggplot2.org/current/geom_bar.html

Upvotes: 1

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