First of all, thanks for an excellent package. I have been using tmap for many projects over the years.

This week I was supporting an R training and we gave an introduction to maps using tmap. One of the participants was very keen to have pie charts on the polygon centroids. We tried to figure it out but couldn't manage in the end.

One ray of hope was when we saw the description in tm_symbols() under details saying ' See example of a proportional symbol map with ggplot2 plots.' For the life of me I couldn't find it. Would you be able to point to the example?

Many thanks!