how to automatically skip some x-labels?

[von_olaf]

Consider this simple example

tibble(x = c('2001-01',
             '2001-02',
             '2001-03',
             '2001-04'),
       y = c(10,20,10,3)) %>% 
  ggplot(aes(x = x, y = y)) + geom_col()

which gives

My issue is that I would like to skip every other label for the x-axis.

For instance, only showing 2001-01 but a blank for 2001-02, then showing 2001-03 and then a blank for 2001-04. Nevertheless, I would still like to see a tick for all of them.

How can I do that automatically with ggplot and likely scale_x_discrete?

Thanks!

[woodward]

A simple way is supply the labels manually, and just put "" for the ones you don't want.

df <- your_tibble
xlabels <- sort(unique(df$x))
xlabels[seq(2, length(xlabels), 2)] <- ""

# then use
scale_x_discrete(labels = xlabels)

[von_olaf]

thanks! but is there any way to do it on the fly within the ggplot call?

[woodward]

If you assign the data to some dataframe such as df then you can do it on the fly with a function.

library(tidyverse)

df <- tibble(x = c('2001-01',
             '2001-02',
             '2001-03',
             '2001-04'),
       y = c(10,20,10,3)) 

everysecond <- function(x){
  x <- sort(unique(x))
  x[seq(2, length(x), 2)] <- ""
  x
}

ggplot(data = df) + 
  geom_col(mapping = aes(x = x, y = y)) + 
  scale_x_discrete(labels = everysecond(df$x))

^{Created on 2020-05-13 by the reprex package (v0.3.0)}