Vertical spaces in legend

Question

I am having trouble formatting my legend. I would like to increase the vertical space between each element of the legend.

I post the image it produces and the code so you can help me if you want.

This is the code relative to the legend:

par(fig = c(0, 1, 0, 1), oma = c(0, 0, 0, 0), mar = c(0, 0, 0, 0), new = TRUE)
legend("right", c("$\\lambda < \\lambda_{cr}$ ", "$\\lambda < \\lambda_{cr}$", 
"$\\lambda = \\lambda_{cr}$ ", "$\\lambda = \\lambda_{cr}$ "), xpd = TRUE, 
inset = c(0,0), bty = "n", lty = c(1, 1, 1, 1), lwd=2, col = c("black","green4","red","blue"))

Answer 1

Buried in ?legend we find the relevant arguments:

x.intersp - character interspacing factor for horizontal (x) spacing.

y.intersp - the same for vertical (y) line distances.

To fix your legend, you could start with an interspacing factor of 2, so your legend call would become

legend("right", c(
    "$\\lambda < \\lambda_{cr}$ ",
    "$\\lambda < \\lambda_{cr}$",
    "$\\lambda = \\lambda_{cr}$ ",
    "$\\lambda = \\lambda_{cr}$ "
), xpd = TRUE, inset = c(0,0), bty = "n", lty = c(1, 1, 1, 1),
lwd=2, col = c("black","green4","red","blue"),
y.intersp=2
)

If that gives you too much or too little space between the items, adjust the value accordingly.