How to combine mulitipanelplot objects into 1 page and label them A, B, C ...?

[jarbet]

I have previously used cowplot::plot_grid and gridExtra::grid.arrange to combine multiple BPG plots into a single page, and give the plots labels, e.g. A, B, C..

However, this does not work for plots made from create.multipanelplot.

I am currently trying this option from @raagagrawal (write plots to disk, read them in using cowplot, plot_grid to combine, then save_plot), which I implemented here.

However, I am curious if anyone has other solutions for combining multipanelplots into 1 page and labeling them?

[pboutros]

Yup a couple of suggestions. In write.plot() there is the capability to pass in additional plots and specifically locate them via additional.trellis.objects and additional.trellis.locations. IIRC that was particularly designed for insets, but is likely useful for lots of other things.

But if that doesn't work, I believe the general solution is to do plot(trells.object, newpage = TRUE); for the first one and then for subsequent ones plot(trellis.objection, position = c(coordinates), newpage = FALSE); This should be how write.plot() actually implements the above.

I believe there's an example of the first in write.plot(), and then suggest opening a PR to add an example of the second to write.plot() as well

[jarbet]

Thanks @pboutros. I got your approach to work for overlaying 2 plots into one plot, but what if you want to arrange plots side-by-side and label them A,B,C... something like this:

Do you know if your approach supports that?

At a minimum, I was able to get Raag's solution to work, but still curious about other options.

[pboutros]

It definitely does -- there should be examples on our internal github repo to find, and that's the standard mechanism we'll want to be using.

[stefaneng]

However, this does not work for plots made from create.multipanelplot.

@jarbet
You can actually put multipanelplots together with grid.arrange but the class needs to change.
create.multipanelplot removes the other grob associated class (expect to print: https://github.com/uclahs-cds/public-R-BoutrosLab-plotting-general/blob/main/R/create.multipanelplot.R#L6C17-L6C53). Also, once you change the class to a frame then you can annotate the grob with placeGrob and add text via a textGrob

For example:

library(BoutrosLab.plotting.general);

set.seed(13);
sample.data <- data.frame(x = rnorm(100), y = rnorm(100))
plot1 <- create.scatterplot(
    y ~ x,
    data = sample.data
    );

plot2 <- create.histogram(sample.data$y);

plot1.mpp <- create.multipanelplot(list(plot1), layout.height = 1, layout.width = 1);
plot2.mpp <- create.multipanelplot(list(plot2), layout.height = 1, layout.width = 1);
class(plot1.mpp) <- c('multipanel', 'frame', 'gTree', 'grob', 'gDesc');
class(plot2.mpp) <- c('multipanel', 'frame', 'gTree', 'grob', 'gDesc');

plot1.anno.mpp <- placeGrob(plot1.mpp, textGrob('A', x = 0.1, y = 0.9, gp = gpar(fontface = 'bold', cex = 2)));
plot2.anno.mpp <- placeGrob(plot2.mpp, textGrob('B', x = 0.1, y = 0.9, gp = gpar(fontface = 'bold', cex = 2)));

combined.fig <- gridExtra::grid.arrange(plot1.anno.mpp, plot2.anno.mpp, ncol = 2);

write.plot(
    combined.fig,
    width = 12,
    height = 6,
    filename = 'test.png',
    resolution = 100
    );

I wasn't able to do it via write.plot either. The position argument from print.trellis seems to only place the plot within the current one. This isn't to say it isn't possible, I just couldn't figure out how to do it in my quick search. Github search didn't turn up any examples of this either.

[jarbet]

Although I have used cowplot::plot_grid in the past to combine figures and label them (e.g. a,b,c,d), I recently ran into a scenario where this did not work and I needed to use create.multipanelplot to combine the figures instead.

I can confirm that @stefaneng's above approach works very well! I've simplified it a bit below:

Labeling sub-plots when using create.multipanelplot:

1. Make your bpg plots
2. Make sure the class of each plot is correct, e.g.:

class(plot1.mpp) <- c('frame', 'gTree', 'grob', 'gDesc');

Note if the plots you are combining are each multipanelplots, then you need to add class multipanelplot above

3. Add the labels to each plot, e.g.:

plot1.anno.mpp <- placeGrob(plot1.mpp, textGrob('A', x = 0.1, y = 0.9, gp = gpar(fontface = 'bold', cex = 2)));

4. Combine the new 'annotated' plots using create.multipanelplot

---

A major benefit of this approach is you can add an Overall legend using create.multipanelplot, whereas you cannot do this with cowplot::plot_grid

gridExtra is not needed, the entire above process can be done in BPG