Use ggplot2 to shade the area between two straight lines

Question

First, I initialize the data

set.seed(1)
x <- runif(10000,17,18)
yone <- x+1/4
ytwo <- x-1/4
df <- data.frame(x,yone,ytwo)

Then I create the plot

ggplot(df,aes(x=x)) + 
    geom_line(aes(y=yone)) + 
    geom_line(aes(y=ytwo)) +
    geom_ribbon(aes(ymin = yone, ymax = ytwo),fill='blue',alpha=0.5) +
    geom_hline(yintercept=17) +
    geom_vline(xintercept=17) +
    geom_hline(yintercept=18) +
    geom_vline(xintercept=18) +
    theme_bw() +
    scale_x_continuous(expand=c(0,0), limits = c(17,18)) +
    scale_y_continuous(expand=c(0,0), limits = c(17,18))

There are two trapezoid shaped areas between the lines that are not shaded. I want it to look like:

That area is filled in properly if I dont use scale_x_continuous and scale_y_continuous to restrict the limits of the plot, but that's a necessity.

score 3 · Answer 1 · answered Nov 05 '21 at 02:45

There is a known bug on Windows that effects the clipping of regions that have alpha values set. See the github issue here: https://github.com/tidyverse/ggplot2/issues/4498

The recommended work around is to use the AGG graphics device rather than the default Windows graphic device. Those there is a comment that a fix was incorporated into r-devel (r81114) but that was 4 days ago. This bug appears to still be in 4.1.1 but may be fixed in future R versions.

But even without the bug, don't use scale_x_continuous to zoom in. Use coord_cartesian as described this existing question: ggplot ribbon cut off at y limits

Park · Accepted Answer · 2021-11-05T02:48:37.753

2

You need to use coord_casterian instead of scale_._continous not to remove some values.

ggplot(df,aes(x=x)) + 
    geom_line(aes(y=yone)) + 
    geom_line(aes(y=ytwo)) +
    geom_ribbon(aes(ymin = yone, ymax = ytwo),fill='blue',alpha=0.5) +
    geom_hline(yintercept=17) +
    geom_vline(xintercept=17) +
    geom_hline(yintercept=18) +
    geom_vline(xintercept=18) +
    coord_cartesian(xlim = c(17,18), ylim = c(17,18))

Additional code

df %>%
  rowwise %>%
  mutate(ytwo = max(17, ytwo),
         yone = min(18, yone)) %>%
  ggplot(aes(x=x)) + 
  geom_line(aes(y=yone)) + 
  geom_line(aes(y=ytwo)) +
  geom_ribbon(aes(ymin = yone, ymax = ytwo),fill='blue',alpha=0.5) +
  theme_bw() +
  geom_hline(yintercept=17) +
  geom_vline(xintercept=17) +
  geom_hline(yintercept=18) +
  geom_vline(xintercept=18) +
  coord_cartesian(xlim = c(17,18), ylim = c(17,18))

edited Nov 05 '21 at 02:48

answered Nov 05 '21 at 02:36

Park

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Is there a way to exclude the shaded area below Y=17 and above Y=18? Whether that means to not shade that area or not show it in the plot? – Machetes0602 Nov 05 '21 at 02:41
Nevermind, I figured it out. Just have to add expand=F as a parameter to coord_cartesian and it works. Thanks! – Machetes0602 Nov 05 '21 at 02:48
@Machetes0602 I add the code above. Please check it out. – Park Nov 05 '21 at 02:48

Use ggplot2 to shade the area between two straight lines

2 Answers2

Additional code