Increase number of axis ticks

I'm generating plots for some data, but the number of ticks is too small, I need more precision on the reading.

Is there some way to increase the number of axis ticks in ggplot2?

I know I can tell ggplot to use a vector as axis ticks, but what I want is to increase the number of ticks, for all data. In other words, I want the tick number to be calculated from the data.

Possibly ggplot do this internally with some algorithm, but I couldn't find how it does it, to change according to what I want.

You can override ggplots default scales by modifying scale_x_continuous and/or scale_y_continuous. For example:

library(ggplot2)
dat <- data.frame(x = rnorm(100), y = rnorm(100))

ggplot(dat, aes(x,y)) +
  geom_point()

Gives you this:

And overriding the scales can give you something like this:

ggplot(dat, aes(x,y)) +
  geom_point() +
  scale_x_continuous(breaks = round(seq(min(dat$x), max(dat$x), by = 0.5),1)) +
  scale_y_continuous(breaks = round(seq(min(dat$y), max(dat$y), by = 0.5),1))

If you want to simply "zoom" in on a specific part of a plot, look at xlim() and ylim() respectively. Good insight can also be found here to understand the other arguments as well.

Based on Daniel Krizian's comment, you can also use the pretty_breaks function from the scales library, which is imported automatically:

ggplot(dat, aes(x,y)) + geom_point() +
scale_x_continuous(breaks = scales::pretty_breaks(n = 10)) +
scale_y_continuous(breaks = scales::pretty_breaks(n = 10))

All you have to do is insert the number of ticks wanted for n.

---

A slightly less useful solution (since you have to specify the data variable again), you can use the built-in pretty function:

ggplot(dat, aes(x,y)) + geom_point() +
scale_x_continuous(breaks = pretty(dat$x, n = 10)) +
scale_y_continuous(breaks = pretty(dat$y, n = 10))

You can supply a function argument to scale, and ggplot will use that function to calculate the tick locations.

library(ggplot2)
dat <- data.frame(x = rnorm(100), y = rnorm(100))
number_ticks <- function(n) {function(limits) pretty(limits, n)}

ggplot(dat, aes(x,y)) +
  geom_point() +
  scale_x_continuous(breaks=number_ticks(10)) +
  scale_y_continuous(breaks=number_ticks(10))

Starting from v3.3.0, ggplot2 has an option n.breaks to automatically generate breaks for scale_x_continuous and scale_y_continuous

	library(ggplot2)

	plt <- ggplot(mtcars, aes(x = mpg, y = disp)) +
	  geom_point()

	plt + 
	  scale_x_continuous(n.breaks = 5)

	plt + 
	  scale_x_continuous(n.breaks = 10) +
	  scale_y_continuous(n.breaks = 10)

Additionally,

ggplot(dat, aes(x,y)) +
geom_point() +
scale_x_continuous(breaks = seq(min(dat$x), max(dat$x), by = 0.05))

Works for binned or discrete scaled x-axis data (I.e., rounding not necessary).

A reply to this question and https://stackoverflow.com/questions/69410603/how-set-labels-on-the-x-and-y-axises-by-equal-intervals-in-r-ggplot

mtcars %>% 
  ggplot(aes(mpg, disp)) +
  geom_point() +
  geom_smooth() + 
  scale_y_continuous(limits = c(0, 500),
                     breaks = seq(0,500,50))  +
  scale_x_continuous(limits = c(0,40),
                     breaks = seq(0,40,5))