I am using this code to produce a heatmap
with Makie
using the backend of CairoMakie
agent_money(xx,yy) = id_in_position( (xx,yy) , schelling ) > 0 ? schelling[ id_in_position( (xx,yy) , schelling ) ].money : -1
xs = 1:13
ys = 1:13
fig, ax, hm = CairoMakie.heatmap(xs, ys, agent_money)
Colorbar(fig[:, end+1], hm)
fig
but some of the squares I just give a -1 value but are actually empty, how do I set them to be ignored or plotted with white or completely separately?