Set Max value for color bar on seaborn heatmap
I think you want to use the vmin and vmax parameters for the heatmap, as described in the docs:
vmin, vmax : floats, optional
Values to anchor the colormap, otherwise they are inferred from the data and other keyword arguments.
sns.heatmap(tiles, robust=True, fmt="f", cmap='RdBu_r', vmin=0, vmax=2)