I don't have your script, nor your data. Therefore I can't say what ff is, nor area.
but assuming you had reason to believe that
ggplot2(ff, aes(x = area)) + geom_histogram()
would work, on that basis, I recommend attempting
ggplot(ff, aes(x = area)) + geom_histogram()
I do most of my plotting with the plotly package (who's main function is plot_ly() hilariously enough
)