CODEWITHSUNDEEP
rggplot2
Pavel Shliaha
Pavel Shliaha

Reputation: 935

create a gradient of size and color of the points in ggplot2 extending beyond the values present

I am building a plot whereby each point has a size and colour based on a linear gradient in two separate columns

df1 <- data.frame (x = c(1:10), y = c(1:10), pointSize = 1:10, pointCol = 1:10)

ggplot(df1, aes(x = x, y = y, colour = pointCol, size = pointSize)) + geom_point() +
   scale_colour_gradient(low = "steelblue", high = "yellow")

the maximum value in the table for columns encoding color and point size are 10. Can I change the gradient sizes so that it goes from say = 10 to 20?

Upvotes: 2

Views: 5147

Answers (1)

Z.Lin
Z.Lin

Reputation: 29085

You can define the same size scale limits for both plots. Here's an example:

Sample datasets:

df1 <- data.frame (x = 1:10, y = 1:10, pointSize = 1:10, pointCol = 1:10)
df2 <- data.frame (x = 1:10, y = 10:1, pointSize = 11:20, pointCol = 1:10)

Plot without standardising the scale for size (we can see size 10 in plot 1 matches size 20 in plot 2):

p1 <- ggplot(df1, aes(x = x, y = y, colour = pointCol, size = pointSize)) + 
  geom_point() +
  scale_colour_gradient(low = "steelblue", high = "yellow") +
  theme_bw()

p2 <- ggplot(df2, aes(x = x, y = y, colour = pointCol, size = pointSize)) + 
  geom_point() +
  scale_colour_gradient(low = "steelblue", high = "yellow") +
  theme_bw()

gridExtra::grid.arrange(p1, p2, nrow = 1)

plot1

Now let's define the same scale limits for both:

size.limits <- range(df1$pointSize, df2$pointSize)

> size.limits
[1]  1 20

Add the scales for size to each plot (we can see now the two plots share the same size legend, and the largest point in plot 1 is the same size as the smallest point in plot 2):

gridExtra::grid.arrange(p1 + scale_size(limits = size.limits), 
                        p2 + scale_size(limits = size.limits), 
                        nrow = 1)

plot2

Upvotes: 6

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