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rplotr-grid

How to add background grid to plot with custom intervals in R?

How can I add a background grid to an R plot such that background lines are evenly spaced one unit apart from each other?

Here is what I've tried so far:

x = 1:10
y = 21:30
plot(x, y, yaxt="n")
axis(2, at=20:30, las=2)
grid(NULL, NULL)

x vs y

Here, I see that this call to grid aligns that grid with the default axis. (In this case, 22, 24, 26, 28, and 30.) However, I wish to align the grid with the new axis, i.e. 21, 22, ... 30. Furthermore, I see that this imposes the grid on top of the points. I'd like to see the grid in the background.

Note: I don't want a solution with absline(), unless it's possible to coerce those lines to the background.

Note 2: This is not a dupe of this question. They just want to add a grid. My question is different in that I want to add the grid in the background, and with custom-spaced lines.

Solution

  • The way to do this is as follows:

    x = 1:10
y = 21:30
plot(x, y, yaxt="n", panel.first = c(abline(h = 21:30, col="grey")), pch=19)
axis(2, at=20:30, las=2)

    Custom intervals can be specified by changing what gets filled into c in the panel.first argument. Meanwhile, the call to axis adds the labels. Finally, this ensures that the grid lines are indeed in the background of the image.

    This is the image produced by this code: enter image description here