Plotting two variables using ggplot2 - same x axis

Question

I have two graphs with the same x axis - the range of x is 0-5 in both of them. I would like to combine both of them to one graph and I didn't find a previous example. Here is what I got:

c <- ggplot(survey, aes(often_post,often_privacy)) + stat_smooth(method="loess")
c <- ggplot(survey, aes(frequent_read,often_privacy)) + stat_smooth(method="loess")

How can I combine them? The y axis is "often privacy" and in each graph the x axis is "often post" or "frequent read". I thought I can combine them easily (somehow) because the range is 0-5 in both of them.

Many thanks!

This is pretty easy by reshaping (reshape2::melt) and then using an aesthetic such as colour (or simply group) to distinguish the two variables. You need to melt in such a way that you keep often_privacy as an id variable. If you post a small subset of your data (with dput) I'm sure you'll get an answer. — Ben Bolker
– Ben Bolker, Commented Jun 28, 2012 at 11:28

Richie Cotton · Accepted Answer · 2012-06-28 17:02:26Z

10

Example code for Ben's solution.

#Sample data
survey <- data.frame(
  often_post = runif(10, 0, 5), 
  frequent_read = 5 * rbeta(10, 1, 1), 
  often_privacy = sample(10, replace = TRUE)
)
#Reshape the data frame
survey2 <- melt(survey, measure.vars = c("often_post", "frequent_read"))
#Plot using colour as an aesthetic to distinguish lines
(p <- ggplot(survey2, aes(value, often_privacy, colour = variable)) + 
  geom_point() +
  geom_smooth()
)

edited Jun 28, 2012 at 17:02

answered Jun 28, 2012 at 12:36

Richie Cotton

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Mathew Hall · Accepted Answer · 2012-06-28 14:03:01Z

4

You can use + to combine other plots on the same ggplot object. For example, to plot points and smoothed lines for both pairs of columns:

ggplot(survey, aes(often_post,often_privacy)) + 
geom_point() +
geom_smooth() + 
geom_point(aes(frequent_read,often_privacy)) + 
geom_smooth(aes(frequent_read,often_privacy))

edited Jun 28, 2012 at 14:03

answered Jun 28, 2012 at 12:23

Mathew Hall

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1 Comment

Ben Bolker Over a year ago

this answers the question nicely, although I think my comment above suggests the more 'idiomatic' way to do it (which among other things provides (1) an automatic legend (2) more compact code [although for only two variables there's not a big advantage])

Sandipan Dey · Accepted Answer · 2016-10-14 05:23:46Z

0

Try this:

df <- data.frame(x=x_var, y=y1_var, type='y1') 
df <- rbind(df, data.frame(x=x_var, y=y2_var, type='y2'))
ggplot(df, aes(x, y, group=type, col=type)) + geom_line()

answered Oct 14, 2016 at 5:23

Sandipan Dey

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