How to use a variable as an argument of ggplot?

Question

Let's consider the following example.

Dat is a data frame with variables y, a, b, and c.

I would like to create three scatter plots where y is on the y axis and a, b, or c is on the x axis.

I used a for loop as follows.

I know x = x in aes(x = x, y = y) is wrong. My question is how to modify x = x to make it work.

library(ggplot2)

x_vec = c("a", "b", "c")

a = 1:10
b = a+10
c = b+10
y = 1:10

Dat = data.frame(y = y, a = a, b = b, c = c)
str(Dat)

p_list = list()

for (i in 1:3) {
    # i = 1
    x = x_vec[i]
    x
    p = ggplot(Dat, aes(x = x, y = y)) +
        geom_point()
    p_list[[i]] = p
}

plot(p_list[[1]])
plot(p_list[[2]])
plot(p_list[[3]])

This is programming rather than statistics

Henry
– Henry

2021-05-17 16:36:27 +00:00
Commented May 17, 2021 at 16:36 — Henry
– Henry, Commented May 17, 2021 at 16:36

akrun · Accepted Answer · 2021-05-17 17:22:38Z

2

We can convert to symbol and evaluate (!!

...
    p = ggplot(Dat, aes(x=!! rlang::sym(x), y=y))+
...

answered May 17, 2021 at 17:22

akrun

891k38 gold badges590 silver badges700 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Thomas Bilach · Accepted Answer · 2021-05-17 17:47:11Z

1

Why not take advantage of ggplot's functionality?

Once your data is in long format it's easier to create small multiples across each category. This answer assumes you want three separate scatterplots. Try this out:

library(ggplot2)
library(dplyr)

a = 1:10
b = a + 10
c = b + 10
y = 1:10

dat <- data.frame(y = y, a = a, b = b, c = c)

dat_long <- dat %>%
  pivot_longer(cols = `a`:`c`, names_to = "labels", values_to = "x") %>%
  arrange(labels)

ggplot(dat_long, aes(x = x, y = y)) +
  geom_point() +
  theme_minimal() +
  facet_wrap(~ labels)

If you must execute this using a for loop, then see the accompanying answer.

answered May 17, 2021 at 17:47

Thomas Bilach

6013 silver badges18 bronze badges

1 Comment

Tom Over a year ago

Thanks. Your alternative solution is better than mine with a for loop.

Collectives™ on Stack Overflow

How to use a variable as an argument of ggplot?

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related