Is there a way to align 2 independent axes in an R graph?

Question

I\'m plotting a graph with different axis. The problem is that I want the 2 axes to be crossing one point, the rest doesn\'t really matter. Is it possible?

Here is a rep

Answer 1

It's not a beautiful solution, but as long as your x-axes always cross the 0 value, you can set the xlim=c(-max(c(-min(x),max(x))),max(c(-min(x),max(x)))) for both plots. This will make the x-axis always center at 0for both the top and bottom axes. The same can be done with the y-axes if you so choose.

# Set graphing parameters
par(mar = c(5,4,4,4) + 0.1) # This can be reset later with "dev.off()"

# Plot the first graph
plot(x = -10:10, y = -10:10, 
     xlim=c(-max(c(-min(x),max(x))),max(c(-min(x),max(x)))),
     xlab="x-label-1",ylab="y-label-1") # Added labels to be changed
abline(v=0,lty = 2)

# Plot the second graph using new axes
par(new =TRUE)
plot(x = -10:50, y = seq(-5,5,length.out = length(-10:50)), 
     xaxt = "n", yaxt = "n", bty ="n",
     xlim=c(-max(c(-min(x),max(x))),max(c(-min(x),max(x)))),
     xlab=NA,ylab=NA) # Remove x- and y-axis labels
abline(v=0,lty = 3)
axis(3, col="red",col.axis="red",las=2, cex.axis = 1)
axis(4, col="red",col.axis="red",las=2, cex.axis = 1)
mtext("x-label-2", side = 3, line = 3, cex = par("cex.lab")) # Labeled secondary x-axis
mtext("y-label-2", side = 4, line = 3, cex = par("cex.lab")) # Labeled secondary y-axis

which gives:

I hope this works! You'll need to play around with the values for par(mar()) if you want to label your graphs with a title.