即使xpd = TRUE，如何绘制垂直和水平线？

Question

Here is a simplified plot to work with:

env <- data.frame(site = c('BLK','DUC','WHP','BLK','DUC','WHP','BLK','DUC','WHP'),
                  sal = c(5,6,3,2,4,5,6,8,4),
                  date = c(2013,2013,2013,2015,2015,2015,2017,2017,2017))
sitelist <- c('BLK','DUC','WHP')
par(mar=c(3,5,3,6), xpd = T)
plot(sal~date, data = env, type = 'n', ylim = c(0,10), ylab = 'Salinity',
     bty = 'n', xlab = '')
abline(v=2016, col = 'khaki', lwd = 20)
abline(mean(env$sal), 0, lty = 3)
for (ii in seq_along(sitelist)) {
  i <- sitelist[ii]; lines(sal[site==i] ~ date[site==i], data = env,
                            col = c(4,2,5)[ii],  lwd = 2,
                            lty = c(1,2,3)[ii]);
  points(sal[site==i] ~ date[site==i], data = env,
         pch = c(0,1,2)[ii], col = c(4,2,5)[ii])}
legend('topright', title = 'sites', inset=c(-0.2,0), lty = c(1,2,3), 
       col = c(4,2,5), lwd = 2, sitelist, 
       pch = c(0,1,2))

As written, this code yields a plot where the abline functions create lines that go outside of the boundaries of the plot, thanks to xpd=T . However, I don't want to set xpd=F , because I won't be able to plot my legend outside of the boundaries. The solution must either be a way to plot a legend outside of the boundaries with xpd=F or a way to plot lines that stop at the boundaries. Ideally, the solution would use the base program and be fairly standard, so I could drop it into each of my ~20 plots without too much customization.

I tried using segments but was not happy with the rounded edges of the segment, as my vertical line is supposed to be a sort of shaded area to indicate a certain time period.

Answer 1

This should solve your issue.

Replace

abline(v=2016, col = 'khaki', lwd = 20)
abline(mean(env$sal), 0, lty = 3)

with

lines(c(2013, 2017), rep(mean(env$sal), 2), col="black", lwd = 2, lty = 2)
lines(rep(2016, 2), c(0, 10), col="khaki", lwd = 20)

Source: https://stackoverflow.com/a/24741885/5874001

par(mar=c(3,5,3,6), xpd = T)
plot(sal~date, data = env, type = 'n', ylim = c(0,10), ylab = 'Salinity', bty = 'n', xlab = '')
lines(c(2013, 2017), rep(mean(env$sal), 2), col="black", lwd = 2, lty = 2)
lines(rep(2016, 2), c(0, 10), col="khaki", lwd = 20)
for (ii in seq_along(sitelist)) {
  i <- sitelist[ii]; lines(sal[site==i] ~ date[site==i], 
                            data = env,
                            col = c(4,2,5)[ii],  
                            lwd = 2,
                            lty = c(1,2,3)[ii]);
  points(sal[site==i] ~ date[site==i], data = env,
         pch = c(0,1,2)[ii], col = c(4,2,5)[ii])}
legend('topright',  title = 'sites', inset=c(-0.2,0), 
       lty = c(1,2,3), col = c(4,2,5), lwd = 2, 
       sitelist, pch = c(0,1,2))

If you have 20+ plots, I'd look to see if you can write a loop to perform that task.

Answer 2

You can either set xpd to FALSE in the par call and insert xpd = TRUE in the legend call like this:

env <- data.frame(site = c('BLK','DUC','WHP','BLK','DUC','WHP','BLK','DUC','WHP'),
                  sal = c(5,6,3,2,4,5,6,8,4),
                  date = c(2013,2013,2013,2015,2015,2015,2017,2017,2017))
sitelist <- c('BLK','DUC','WHP')
par(mar=c(3,5,3,6), xpd = F)
plot(sal~date, data = env, type = 'n', ylim = c(0,10), ylab = 'Salinity',
     bty = 'n', xlab = '')
abline(v=2016, col = 'khaki', lwd = 20)
abline(mean(env$sal), 0, lty = 3)
for (ii in seq_along(sitelist)) {
  i <- sitelist[ii]; lines(sal[site==i] ~ date[site==i], data = env,
                            col = c(4,2,5)[ii],  lwd = 2,
                            lty = c(1,2,3)[ii]);
  points(sal[site==i] ~ date[site==i], data = env,
         pch = c(0,1,2)[ii], col = c(4,2,5)[ii])}
legend('topright', title = 'sites', inset=c(-0.2,0), lty = c(1,2,3), 
       col = c(4,2,5), lwd = 2, sitelist, 
       pch = c(0,1,2),
     xpd = T)

Or keep xpd = TRUE in the par call and set xpd to FALSE in the abline calls like this:

env <- data.frame(site = c('BLK','DUC','WHP','BLK','DUC','WHP','BLK','DUC','WHP'),
                  sal = c(5,6,3,2,4,5,6,8,4),
                  date = c(2013,2013,2013,2015,2015,2015,2017,2017,2017))
sitelist <- c('BLK','DUC','WHP')
par(mar=c(3,5,3,6), xpd = T)
plot(sal~date, data = env, type = 'n', ylim = c(0,10), ylab = 'Salinity',
     bty = 'n', xlab = '')
abline(v=2016, col = 'khaki', lwd = 20,xpd=F)
abline(mean(env$sal), 0, lty = 3,xpd=F)
for (ii in seq_along(sitelist)) {
  i <- sitelist[ii]; lines(sal[site==i] ~ date[site==i], data = env,
                            col = c(4,2,5)[ii],  lwd = 2,
                            lty = c(1,2,3)[ii]);
  points(sal[site==i] ~ date[site==i], data = env,
         pch = c(0,1,2)[ii], col = c(4,2,5)[ii])}
legend('topright', title = 'sites', inset=c(-0.2,0), lty = c(1,2,3), 
       col = c(4,2,5), lwd = 2, sitelist, 
       pch = c(0,1,2))