Sorry but I fail to see how is smoother, I just can see a fill gradient on grayscale without borders, try with less saturated colors for your fill scale and take out the borders.
library(ggplot2)
SLOAN <- data.frame(
Xpos = c(45, 20, 32, 45),
Ypos = c(10, 27, 10, 6),
P = c(0.758, 0.126, 0.068, 0.493)
)
ggplot(SLOAN,aes(x=Xpos,y=Ypos, z = P)) +
stat_summary_hex() +
scale_fill_gradient(low = "#FFFF0064", high = "#F02B2B70") +
xlim(0, 50) +
ylim(0, 47) +
geom_rug(alpha = 0.2) +
theme_minimal() +
theme(panel.grid = element_blank()) +
coord_fixed()
