Can't change color palette when filling by continuous variable

[wilkox]

Can't change color palette when filling by continuous variable

[wilkox]

Hi Zach,

The issue here is that you are (correctly) using the fill aesthetic, but trying to modify it with scale_colour_*() functions instead of scale_fill_*() functions. For the first example, if you use scale_fill_gradient2() it should work as expected:

ggplot(example_genes, aes(xmin = start, xmax = end, y = molecule, fill = start)) +
  geom_gene_arrow() +
  facet_wrap(~ molecule, scales = "free", ncol = 1) +
  scale_fill_gradient2()

^{Created on 2021-12-15 by the reprex package (v2.0.1.9000)}

For the second example, if you just change scale_colour_brewer() to scale_fill_brewer(), you'll get an error because the Brewer scales (as implemented in ggplot2) are designed for discrete variables:

ggplot(example_genes, aes(xmin = start, xmax = end, y = molecule, fill = start)) +
  geom_gene_arrow() +
  facet_wrap(~ molecule, scales = "free", ncol = 1) +
  scale_fill_brewer(palette = "Greens")
#> Error: Continuous value supplied to discrete scale

^{Created on 2021-12-15 by the reprex package (v2.0.1.9000)}

Instead you can use the scale_*_distiller() functions which will interpolate the Brewer palettes for continuous variables:

ggplot(example_genes, aes(xmin = start, xmax = end, y = molecule, fill = start)) +
  geom_gene_arrow() +
  facet_wrap(~ molecule, scales = "free", ncol = 1) +
  scale_fill_distiller(palette = "Greens")

^{Created on 2021-12-15 by the reprex package (v2.0.1.9000)}

[zreitz]

Oh of course! Thank you the quick reply!