I want to change the default thickness of geom_line using the size aesthetic. This question has already been answered here but the solution – to set the default value using update_geom_defaults does not work for me.

Here’s a minimum reproducible example:

library(tidyverse)

update_geom_defaults("line", list(size = 2))

data(ChickWeight)

ChickWeight %>%
  filter(Chick %in% c("1", "2", "3")) %>%
  ggplot(aes(x = Time, y = weight, colour = Chick)) +
  geom_line()

The result I get is:

update_geom_defaults does work for changing e.g. the default colour. Any idea what’s going on here and how to successfully change the default size?

>Solution :

You could use linewidth to change the thickness like this:

library(tidyverse)

update_geom_defaults("line", list(linewidth = 2))

data(ChickWeight)

ChickWeight %>%
  filter(Chick %in% c("1", "2", "3")) %>%
  ggplot(aes(x = Time, y = weight, colour = Chick)) +
  geom_line()

^{Created on 2023-02-02 with reprex v2.0.2}