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rggplot2

How do I adjust visibility of gridlines in ggplot chart

The code below creates a scatter plot and uses theme_bw with has gridlines in the background -

data = mtcars

data %>% 
  select(mpg, disp) %>% 
  ggplot(aes(disp, mpg))+
  geom_point(size = 3)+
  theme_bw()

I would like to also include some vertical and horizontal lines on the chart. However with the current gridlines, it looks a bit busy. Is there a way to further reduce the visibility of the gridlines. I don't want want remove them completely.

Solution

  • This could be achieved by switching to a lighter color or by reducing the opacity of the color used for the grid lines which both could be achieved via theme option panel.grid. Below I show the second approach. Unfortunately element_line has no alpha argument to set the opacity but we can use scales::alpha() to this end:

    library(ggplot2)
library(dplyr, warn = FALSE)

data <- mtcars

col_grid <- scales::alpha("grey92", .6)

data %>%
  select(mpg, disp) %>%
  ggplot(aes(disp, mpg)) +
  geom_point(size = 3) +
  theme_bw() +
  theme(panel.grid = element_line(color = col_grid))