plotting contours in ggplot - geom_raster, geom_contour, geom_point

Question

I have an interpolated dataset that I want to plot. When I plot it as geom_point, I see a lot of features that I am missing when I use geom_raster or geom_contour. Im guessing it got smoothed over? Is there a way I can plot this without losing the finer grain contours picked up in the geom_point? and the second figure looks terrible! is there a way to smooth this?

ggplot() + geom_raster(data = df, 
                             aes(x=X, y = Y, fill=Z)) + scale_y_reverse() +
scale_fill_distiller(palette = "RdYlBu") +
theme_bw() + theme(panel.grid = element_blank()))


 ggplot(data=df, aes(x = X, y = Y)) +
  geom_point(aes(colour = Z)) + scale_y_reverse() +
scale_colour_gradientn(colours = rev(ODV_colours)) +
theme_bw() + theme(panel.grid = element_blank()))

Answer 1

It seems that you have a low resolution raster and you want to interpolate to make this less blocky. You could use interp for 2-D interpolation in this instance:

library(interp)
library(ggplot2)

ODV_colours <- c('#fca878', '#d42b28', '#fbbf00', '#2cab1a', 
                 '#19b3e6', '#6f44fc', '#c767fa')


interp(x = df$X, y = df$Y, z = df$Z, nx = 1000, ny = 1000, linear = FALSE) |> 
  interp2xyz() |>
  as.data.frame() |>
  ggplot(aes(x, y, fill = z)) +
  geom_raster() +
  scale_y_reverse() +
  scale_fill_gradientn(colours = rev(ODV_colours), na.value = NA) +
  theme_bw(base_size = 16) + 
  theme(panel.grid = element_blank())