Add gradient color within groups in ggplot2 - r

Question

I need help in order to add colors to ggplot objects (specificaly geom_bar).
Here is my data
Names Family Groups Values
H.sapiens A G1 2
H.erectus A G1 6
H.erectus B G2 12
M.griseus C G2 3
A.mellifera D G3 3
L.niger D G3 8
H.erectus D G3 2
L.niger A G1 3
L.niger B G2 3
A.mellifera A G1 8
And so far I suceeded to create this plot :
with this code :
library(ggplot2)
library(ggstance)
library(ggthemes)
ggplot(table, aes(fill=Family, y=Names, x=Values)) +
geom_barh(stat="identity",colour="white")+ theme_minimal() +
scale_x_continuous(limits = c(0,60), expand = c(0, 0))
and now I would like to change the color depending of Groups. More precisely I would like to choose a major color for each group, for instance: G1= blue ; G2 = Green ; G3= Red.
and for each Family to get a gradient within these colors. For instance, B will be darkblue and C ligthblue.
Does someone have an idea, please ?
Here are the data :
dput(table)
structure(list(Names = structure(c(3L, 2L, 2L, 5L, 1L, 4L, 2L,
4L, 4L, 1L), .Label = c("A.mellifera", "H.erectus", "H.sapiens",
"L.niger", "M.griseus"), class = "factor"), Family = structure(c(1L,
1L, 2L, 3L, 4L, 4L, 4L, 1L, 2L, 1L), .Label = c("A", "B", "C",
"D"), class = "factor"), Groups = structure(c(1L, 1L, 2L, 2L,
3L, 3L, 3L, 1L, 2L, 1L), .Label = c("G1", "G2", "G3"), class = "factor"),
Values = c(2L, 6L, 12L, 3L, 3L, 8L, 2L, 3L, 3L, 8L)), class = "data.frame", row.names = c(NA,
-10L))

Answer 1

You may perhaps tweak this one to suit your requirements (I have changed your sample data a bit to show you different gradient among same Group)
df <- read.table(header = T, text = "Names Family Groups Values
H.sapiens A G1 2
H.erectus B G1 6
H.erectus B G2 12
M.griseus C G2 3
A.mellifera D G3 3
L.niger D G3 8
H.erectus A G3 2
L.niger A G1 3
L.niger B G2 3
A.mellifera C G1 8")
library(tidyverse)
df %>% ggplot() +
geom_col(aes(x = Names, y = Values, fill = Groups, alpha = as.integer(as.factor(Family)))) +
coord_flip() +
scale_fill_manual(name = "Groups", values = c("blue", "green", 'red')) +
scale_alpha_continuous(name = "Family", range = c(0.2, 0.7)) +
theme_classic()
Created on 2021-06-12 by the reprex package (v2.0.0)

Answer 2

We can create range of colours for each Group then match on order of Family. You might need to play around with colours to make the difference more prominent:
cols <- lapply(list(G1 = c("darkblue", "lightblue"),
G2 = c("darkgreen", "lightgreen"),
G3 = c("red4", "red")),
function(i) colorRampPalette(i)(length(unique(table$Family))))
table$col <- mapply(function(g, i) cols[[ g ]][ i ],
g = table$Groups, i = as.numeric(table$Family))
ggplot(table, aes(x = Values, y = Names, fill = col )) +
geom_barh(stat = "identity", colour = "white") +
scale_x_continuous(limits = c(0, 60), expand = c(0, 0)) +
scale_fill_identity() +
theme_minimal()