Adjust grid in R plot

Question

I'm ploting a vector of 29 values in a plot using:

plot(0:29, v, type="o", main="Title of the plot")

I try to adjust the grid to be unit by unit using:

grid(31, lw=2)

The problem is that x axis first value (0 position) doesn't start at the begining of the graph and grid starts at the begining, so both elements aren't aligned.

How can solve this issue?

Answer 1

Use abline instead.

plot(0:10)
abline(h = 0:10)
abline(v = 0:10)

You can also force the exact x and y limits:

plot(0:10, 0:10, xlim = c(0,10), ylim = c(0, 10), xaxs = "i", yaxs = "i")
grid(10)

In general, using abline is easier and more robust. I also often plot with type = "n" , add lines/whatever in the background, then add the points.