问题
Similar to Getting ggvis::export_png() working but I'm trying to get this working in RStudio on Windows.
I've installed node.js and downloaded vega and added ./bin to my PATH, but I get the error
mtcars %>% ggvis(~wt, ~mpg) %>% layer_points() %>% export_png
Writing to file plot.png
Error in vega_file(vis, file = file, type = "png") :
Conversion program vg2pngnot found.
来源：https://stackoverflow.com/questions/27002277/ggvisexport-png-on-windows