The problem with R visual is that it's not interactive with other visuals. There is a need to have a plot as described above and click to any bar and get more specific information for that cell in other tabular visual. It can't be done by simply R visual.
I understand your requirement now, while there is no such visual in Power BI desktop. After research, I find a custom visual (Table Sort), which is same with what you want but closer to. Please see the following screenshot. For same STR, cat a and b are shown in different colors.