The plots in party
and its successor package partykit
are implemented in grid
and hence the base
graphics options from par()
such as mfrow
do not work. In addition to the remarks from the comments, you can use grid.layout()
to achieve similar results.
Doing so in plain grid is a bit technical but the code should not be too hard to follow:
grid.newpage()
pushViewport(viewport(layout = grid.layout(2, 1)))
pushViewport(viewport(layout.pos.row = 1, layout.pos.col = 1))
plot(airct, newpage = FALSE)
popViewport()
pushViewport(viewport(layout.pos.row = 2, layout.pos.col = 1))
plot(irisct, newpage = FALSE)
popViewport()
The reason for the newpage = FALSE
argument is that by default the plot is drawn on a new page, rather than adding to a potentially existing plot.