Create common colorkey for two heatmaps in multipanelplot

[stefaneng]

library(BoutrosLab.plotting.general);

set.seed(13);
dat1 <- matrix(rnorm(100), nrow = 10, ncol = 10);
dat2 <- matrix(rnorm(100), nrow = 10, ncol = 10);

at <- seq(-3, 3, length.out = 10);
p1 <- create.heatmap(
    dat1,
    at = at,
    clustering.method = 'none',
    same.as.matrix = TRUE,
    print.colour.key = FALSE
    );

p2 <- create.heatmap(
    dat2,
    at = at,
    clustering.method = 'none',
    same.as.matrix = TRUE,
    print.colour.key = FALSE
    );

# NOTE: This is a bug in create.colourkey. Opens a null device to write the output to
png(nullfile())
colourkey <- create.colourkey(
    x = dat1,
    at = at,
    colourkey.labels.cex = 2.5,
    placement = viewport(
        just='center',
        x = 0.5,
        y = 1,
        width = 0.5,
        height = 0.1
        )
    );

# NOTE: This is a bug in create.colourkey. Close the null device we opened
dev.off();
#> Error in dev.off(): QuartzBitmap_Output - unable to open file '/dev/null'

filename <- tempfile('example_shared_colourkey', fileext = '.png');
create.multipanelplot(
    plot.objects = list(p1, p2),
    layout.width = 2,
    layout.height = 1,
    width = 10,
    height = 6,
    resolution = 200,
    legend = list(
        bottom = list(
            fun = colourkey
            )
        ),
    filename = filename
    );

# To ensure that width/height are maintained by github/reprex
# All this does it load and print the png we saved
grid::grid.raster(png::readPNG(filename))

^{Created on 2023-07-20 with reprex v2.0.2}