如何更改 ggplot 中条形图的 colors 保持图例变量相同？

Question

I would like to have a colorblind friendly paletter for a barplot in ggplot. I plot the barplot through this code

library(tidyverse)
my_se <- df %>%
  group_by(groups) %>%
  summarise(n=n(),
            sd=sd(mean),
            se=sd/sqrt(n))


    # Standard error
    df %>% 
      left_join(my_se) %>% 
      mutate(zone = factor(zone,labels = c("x1","x2","x3","x4","x5","x6","x7","x8","x9","x10","x11"))) %>% 
      ggplot(aes(x=zone, y=mean, fill = groups)) + 
      geom_col(position = position_dodge()) +
      geom_errorbar(aes(x=zone, ymin=mean-se, ymax=mean+se), width=0.4, position = position_dodge(.9)) +
      ggtitle("using standard error")+scale_fill_discrete(labels = c("GC", "IP", "MR","CS"))+
      labs(y= an, x = "Land Cover")+theme_bw()+theme(legend.title =element_blank())+
      theme(legend.text=element_text(size=11),axis.text.y=element_text(size=11.5),
            axis.text.x=element_text(size=11.5),axis.title.x = element_text(size = 12), axis.title.y = element_text(size = 12))

I have made a custom color palette

cbPalette <- c("#999999", "#E69F00", "#56B4E9", "#009E73")

But when I add this snippet code:

scale_fill_manual(values=cbPalette)

to my ggplot code it gives me this message

Scale for 'fill' is already present. Adding another scale for 'fill', which
will replace the existing scale.

Although the colors are changed but my whole legend labels get changed with it. I want to keep my legend variables as "GC", "IP", "MR","CS".

How can I change the colors of the bars with not effecting the legend labels of variables?

Answer 1

Pointing out to great suggestion from @Dave2e you can try this (Data used from similar questions you posted):

df %>% 
  left_join(my_se) %>% 
  mutate(zone = factor(zone,labels = c("x1","x2","x3","x4","x5","x6","x7","x8","x9","x10","x11"))) %>% 
  ggplot(aes(x=zone, y=meangpp, fill = groups)) + 
  geom_col(position = position_dodge()) +
  geom_errorbar(aes(x=zone, ymin=meangpp-se, ymax=meangpp+se), width=0.4, position = position_dodge(.9)) +
  ggtitle("using standard error")+
  scale_fill_manual(labels = c("GC", "IP", "MR","CS"),values=cbPalette)+
  labs(y= 'an', x = "Land Cover")+theme_bw()+theme(legend.title =element_blank())+
  theme(legend.text=element_text(size=11),axis.text.y=element_text(size=11.5),
        axis.text.x=element_text(size=11.5),axis.title.x = element_text(size = 12), axis.title.y = element_text(size = 12))