Imputing new axis tick labels using seqrplot command

Question

I'm using the R packages TraMineR to compute and analyze state sequences. I'm trying to plot with seqrplot command and to change the x axis tick labels. The code would be, for example:

library("TraMineR")
data("mvad")
mvad.alphab <- c("employment", "FE", "HE", "joblessness", "school", "training")
mvad.seq <- seqdef(mvad, 17:86, xtstep = 6, alphabet = mvad.alphab)
mvad.dist<-seqdist(mvad.seq, method="DHD")

seqrplot(mvad.seq, dist.matrix = mvad.dist,
         criterion = "density", nrep = 1, title = "End CS qualification",
         border = NA, axes=FALSE)
axis(1, at = c(1, 6, 12, 18, 24, 30, 36, 42, 48, 54,60,66,70), 
     labels = c(1, 6, 12, 18, 24, 30, 36, 42, 48, 54,60,66,70))

The x axis disappears but the new axis with the imputed thick values appears somewhere at the very bottom right of the plot. In other words, it doesn't replace the deleted axis. Does anyone know what I'm doing wrong? Thank you

Answer 1

The problem is that by default seqrplot (as other plot functions of the seq?plot family) automatically displays the color legend together with the plot, and uses layout to organize the plot and the legend in a single graphic. If you want to act on the axes, you should disable the automatic legend by setting withlegend = FALSE, and then display the legend my hand. For example:

opar <- par(mfrow=c(1,2))
seqrplot(mvad.seq, dist.matrix = mvad.dist,
         criterion = "density", nrep = 1, title = "End CS qualification",
         border = NA, axes=FALSE, withlegend=F)
axis(1, at = c(1, 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 70), 
     labels = c(1, 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 70))
seqlegend(mvad.seq)
par(opar)