2 min read

Set cell_fun/layer_fun in InteractiveComplexHeatmap

2022-04-01

In the interactive heatmap produced by InteractiveComplexHeatmap package, the sub-heatmap is just a zooming of the main heatmap, which means, if cell_fun or layer_fun is set in Heatmap(), both main heatmap and sub-heatmap will execute it. cell_fun and layer_fun provides a way to customize the heatmap cells, but when the main heatmap is huge, adding more graphics via cell_fun/layer_fun apparently is not a good idea. Users may want to suppress cell_fun/layer_fun (or just draw very simple graphics which will not disturb the reading of the heatmap) in the main heatmap, while only to execute them in the sub-heatmap.

Now in InteractiveComplexHeatmap, there is a new function is_in_sub_heatmap() which tells whether the current environment is in main heatmap or in the sub heatmap. This function can be used inside cell_fun/layer_fun so that users can decide which graphics are only drawn for sub-heatmaps.

In the following example, I defined a cell_fun which draws cells as round rectangles, and only in the sub-heatmap, the values in the matrix are added as text labels.

library(InteractiveComplexHeatmap)
library(ComplexHeatmap)

m = matrix(rnorm(100), 10)

ht = Heatmap(m, rect_gp = gpar(type = "none"),
    show_row_dend = FALSE, show_column_dend = FALSE,
    cell_fun = function(j, i, x, y, w, h, fill) {
        grid.roundrect(x, y, w, h, r = unit(0.2, "snpc"),
            gp = gpar(col = "white", fill = fill, lwd = 2))
        
        if(is_in_sub_heatmap()) {
            grid.text(round(m[i, j], 1), x, y)
        }
    })

htShiny(ht)

image