Order of factor levels in facet_wrap

Question

I\'d like to produce a facet_wrap where the order of factors within facets is based on the one of the column factor order. The heart of the problem is each group has duplica

Answer 1

This old question has already an accepted answer. But as it is being used as a dupe target, I feel obliged to suggest a slightly improved and more concise variant.

It's based on the recent enhancements of the ggplot2 package, namely the labels parameter to scale_x_discrete(), and Hadley's forcats package released to CRAN in August 2016. The proposed solution enhances the accepted answer by using material from this answer.

Prepare data

df_ex as provided by the OP needs to be modified to include a variable which guarantees an overall sort order across all facets:

library(dplyr)   # version 0.5.0 used 
df_ex <- df_ex %>% mutate(ordered = paste0(No, address) %>% 
                   forcats::fct_inorder())

The additional column to df_ex now looks as follows:

  address    No   clas ordered
        
1       A     1   Good      1A
2       B     1   Ugly      1B
3       C     1   Ugly      1C
4       A     2   Good      2A
5       C     2    Bad      2C
6       B     2   Ugly      2B
7       C     3   Good      3C
8       A     3    Bad      3A
9       B     3    Bad      3B

As df_ex already had been sorted in the desired order using arrange(), fct_inorder() returns the new column ordered with the levels in the same order as their first appearance.

Plotting

Instead of address, ordered is plotted on the x-axis. The parameter scales = "free_x" to facet_wrap() ensures that unused levels will be dropped from the facets. However, the labels on the x-axis need to be be replaced by supplying a named vector to the labels parameter of scale_x_discrete().

library(ggplot2)   # version 2.2.1 used
ggplot(df_ex, aes(x=ordered,y="",fill=clas)) + #x axis bias voltage dependence
  geom_tile() + 
  scale_fill_manual(values=c('Good'="green","Bad"="Blue","Ugly"="black"))+
  facet_wrap(~No,ncol=1,scales = "free_x")+
  theme(legend.position = "top",axis.text.y = element_text(size = 20,angle = 90),axis.text.x = element_text(size=12,face="bold",colour = "black"),
        axis.title.y = element_text(face="bold",size = 20, colour = "black"),
        axis.title.x = element_text(face="bold",size = 20 , colour = "black"),
        strip.text = element_text(size=26, face="bold"),
        strip.background = element_rect(fill="#FFFF66", colour="black", size=0.5),
        plot.title=element_text(face="bold",color="red",size=14),
        legend.title = element_text(colour="black", size=26,face="bold"),
        legend.text = element_text(colour="black", size=18))+
  labs(x = "address",y = "") + 
  scale_x_discrete(labels = setNames(df_ex$address, df_ex$ord)) +