R - Inserting function into ggplot for modifying axis

Question

I like my ggplots to have the axis always start at 0, so I use this code within my ggplot to do it :

coord_cartesian(xlim = c(0,max(df$A)), ylim = c(0,max(df$B))) +
scale_x_continuous(expand = c(0, 0)) +
scale_y_continuous(expand = c(0, 0)) +

As a full reproducible example:

df = tibble(A = sample(1:100,100, replace = TRUE), B = seq(1,100))

df  %>% 
    filter(A > 30)  %>% 
    ggplot(aes(A, B)) +
        geom_point() +
        coord_cartesian(xlim = c(0,max(df$A)), ylim = c(0,max(df$B))) +
        scale_x_continuous(expand = c(0, 0)) +
        scale_y_continuous(expand = c(0, 0))

Now, those 3 lines are a pain to remember, and quite bloated.

Is there a way I can put those 3 lines into a function, and call it within the ggplot whenever I want to limit my axis?

I saw this link:

ggplot - function for graph styling

Which you can use a function for the theme() part, but I am not sure how to do it for just those 3 lines I put above i.e. coord_cartesian, scale_x etc.

I.e. I want to do something like this:

df  %>% 
    filter(A > 30)  %>% 
    ggplot(aes(A, B)) +
        geom_point() +
        fix_the_axis()

Many thanks

Hey, unfortunately doesnt do exactly what I want. It still leaves that padding around the 0, which is made more pronounced when you have a border around the chart :/ — Nicholas
– Nicholas, Commented Oct 21, 2019 at 11:08

thothal · Accepted Answer · 2019-10-21 12:23:59Z

2

Just return a list with the 3 elements and add that to your plot (ggplot understands list arguments):

zero_line <- function() {
   list(expand_limits(x = 0, y = 0),
        scale_x_continuous(expand = c(0, 0)),
        scale_y_continuous(expand = c(0, 0)))
}

df  %>% 
    filter(A > 30)  %>% 
    ggplot(aes(A, B)) +
        geom_point() +
        zero_line()

answered Oct 21, 2019 at 12:23

thothal

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2 Comments

Nicholas Over a year ago

Exactly what I want, thank you thothal; this is going to save me a lot of time!

Mojoesque Over a year ago

Very nice! Much cleaner than my approach.

Mojoesque · Accepted Answer · 2019-10-21 11:56:17Z

2

I am not sure how exactly you would go about it using the + annotation, but here is one approach:
Defining the function:

fix_axis = function(df_plot) {
  df_plot +
    expand_limits(x = 0, y = 0) +
    scale_x_continuous(expand = c(0, 0)) +
    scale_y_continuous(expand = c(0, 0))
}

Now there are two ways I see to apply it that are both not as smooth as using the + annotation:

Using a bit awkward brackets:

df_plot_fixed = (df  %>% 
    filter(A > 30)  %>% 
    ggplot(aes(A, B)) +
        geom_point()) %>%
        fix_axis()

Using an extra line for the function call:

df_plot_fixed = df  %>% 
    filter(A > 30)  %>% 
    ggplot(aes(A, B)) +
        geom_point()

df_plot_fixed = df_plot_fixed %>%
  fix_axis()

These do what you want them to do and are maybe a bit smoother than always adding the three lines separately, but still not the perfect solution I assume.

This is the resulting plot:

edited Oct 21, 2019 at 11:56

answered Oct 21, 2019 at 11:49

Mojoesque

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1 Comment

Nicholas Over a year ago

Thank you, this is great! :)

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