Possible to animate polygon fill using gganimate in R?
问题 I have county level data recording the year an invasive insect pest was first detected in that county between 2002 and 2018. I created a map using ggplot2 and the maps package that fills the county polygons with a color according to the year the pest was detected. **Is there a way to use the gganimate package to animate this map with the first frame filling in only polygons with a detection date of 2002, the second frame filling polygons with a detection date of 2003 or earlier (so 2002 and