Ggplot2: Group X Axis Discrete Values into Subgroups

ggplot2: group x axis discrete values into subgroups

Two approaches:

Example data:

dat <- data.frame(value=runif(26)*10,
                  grouping=c(rep("Group 1",10),
                             rep("Group 2",10),
                             rep("Group 3",6)),
                  letters=LETTERS[1:26])

head(dat)
     value grouping letters
1 8.316451  Group 1       A
2 9.768578  Group 1       B
3 4.896294  Group 1       C
4 2.004545  Group 1       D
5 4.905058  Group 1       E
6 8.997713  Group 1       F

Without facetting:

ggplot(dat, aes(grouping, value, fill=letters, label = letters)) + 
     geom_bar(position="dodge", stat="identity") + 
     geom_text(position = position_dodge(width = 1), aes(x=grouping, y=0))

With facetting:

ggplot(dat, aes(letters,value, label = letters)) + 
     geom_bar(stat="identity") + 
     facet_wrap(~grouping, scales="free")

Facetting has the obvious advantage of not having to muck about with the positioning of the labels.

subgroups for discrete x Axis in ggplot2

We can use position_dodge:

library(ggplot2)
ggplot(data=df, aes(x=group, y= value, color=subgroup))+
  geom_point(position=position_dodge(width=0.5))+
  ggtitle("How it is")

---

Data

set.seed(1)
df <- data.frame(
    ID =       rep(seq(1,8),2),
    group =    rep(LETTERS[1:4],4),
    subgroup = c(rep("a",8),rep("b",8)),
    value = runif(16)
)

Add subgroup labels/order elements on x-axis in ggplot2 r

One suggestion is to use an ordered factor. For the levels of the factor concatenate Origin and Participant. For the labels of the factor, concatenate Participant and Origin.

# The unique values from the column 'Origin_Participant' will act as the levels
# of the factor. The order is imposed by 'Origin', so that participants from
# same country group together.
Data$Origin_Participant <- paste(Data$Origin, Data$Participant, sep = "\n")
# The unique values from 'Participant_Origin' column will be used for the
# factor' labels (what will end up on the plot).
Data$Participant_Origin <- paste(Data$Participant, Data$Origin, sep = "\n")
# Order data.frame by 'Origin_Participant'. Is also important so that the levels
# correspond to the labels of the factor when creating it below.
Data <- Data[order(Data$Origin_Participant),]
# Or in decreasing order if you need
# Data <- Data[order(Data$Origin_Participant, decreasing = TRUE),]

# Finally, create the needed factor.
Data$Origin_Participant <- factor(x = Data$Origin_Participant,
                                  levels = unique(Data$Origin_Participant),
                                  labels = unique(Data$Participant_Origin),
                                  ordered = TRUE)

library(ggplot2)
# Reuse your code, but map the factor `Origin_Participant` into x. I think there
# is no need of a grouping factor. I also added vjust = 0.5 to align the labels
# on the vertical center.
ggplot(Data, aes(y=Percentage, x = Origin_Participant))+
  geom_point(aes(color = Task))+ 
  geom_line(arrow = arrow(length=unit(0.30,"cm"), type = "closed"), size = .3)+
  facet_grid(~Treatment, scales = "free_x", space = "free_x")+ 
  theme(axis.text.x = element_text(angle = 90, hjust = 1, vjust = 0.5))

If you do not care that Origin appears first in the labels, then is few steps shorter:

Data$Origin_Participant <- factor(x = paste(Data$Origin, Data$Participant, sep = "\n"),
                                  ordered = TRUE)
ggplot(Data, aes(y=Percentage, x = Origin_Participant))+
  geom_point(aes(color = Task))+ 
  geom_line(arrow = arrow(length=unit(0.30,"cm"), type = "closed"), size = .3)+
  facet_grid(~Treatment, scales = "free_x", space = "free_x")+ 
  theme(axis.text.x = element_text(angle = 90, hjust = 1, vjust = 0.5))

Multirow axis labels with nested grouping variables

You can create a custom element function for axis.text.x.

library(ggplot2)
library(grid)

## create some data with asymmetric fill aes to generalize solution 
data <- read.table(text = "Group Category Value
                   S1 A   73
                   S2 A   57
                   S3 A   57
                   S4 A   57
                   S1 B   7
                   S2 B   23
                   S3 B   57
                   S1 C   51
                   S2 C   57
                   S3 C   87", header=TRUE)

# user-level interface 
axis.groups = function(groups) {
  structure(
    list(groups=groups),
    ## inheritance since it should be a element_text
    class = c("element_custom","element_blank")  
  )
}
# returns a gTree with two children: 
# the categories axis
# the groups axis
element_grob.element_custom <- function(element, x,...)  {
  cat <- list(...)[[1]]
  groups <- element$group
  ll <- by(data$Group,data$Category,I)
  tt <- as.numeric(x)
  grbs <- Map(function(z,t){
    labs <- ll[[z]]
    vp = viewport(
             x = unit(t,'native'), 
             height=unit(2,'line'),
             width=unit(diff(tt)[1],'native'),
             xscale=c(0,length(labs)))
    grid.rect(vp=vp)
    textGrob(labs,x= unit(seq_along(labs)-0.5,
                                'native'),
             y=unit(2,'line'),
             vp=vp)
  },cat,tt)
  g.X <- textGrob(cat, x=x)
  gTree(children=gList(do.call(gList,grbs),g.X), cl = "custom_axis")
}

## # gTrees don't know their size 
grobHeight.custom_axis = 
  heightDetails.custom_axis = function(x, ...)
  unit(3, "lines")

## the final plot call
ggplot(data=data, aes(x=Category, y=Value, fill=Group)) + 
  geom_bar(position = position_dodge(width=0.9),stat='identity') +
  geom_text(aes(label=paste(Value, "%")),
            position=position_dodge(width=0.9), vjust=-0.25)+
  theme(axis.text.x = axis.groups(unique(data$Group)),
        legend.position="none")

ggplot - geom_bar with subgroups stacked

This is possible but requires a bit of sleight-of-hand. You would need to use a continuous x axis and label it like a discrete axis. This requires a bit of data manipulation:

library(tidyverse)

data %>%
  mutate(category = as.numeric(interaction(Round,Var1)),
         category = category + (category %% 2)/5 - 0.1,
         Round_cat = factor(Round_Refr, labels = c("1", "2", "Break")),
         Round_cat = factor(Round_cat, c("Break", "1", "2"))) %>%
  group_by(Var1, Round) %>%
  mutate(pertotal = ifelse(Round == 2 & Refreshment == 0,
                           pertotal - pertotal[Round_Refr > 2], pertotal)) %>%
  ggplot(aes(x = category, y = pertotal)) + 
  geom_col(aes(fill = Round_cat), color="white")+
  scale_y_continuous(labels=scales::percent)+ 
  scale_x_continuous(breaks = c(1.5, 3.5, 5.5), 
                     labels = levels(factor(data$Var1))) +
  xlab("category")+
  ylab("Percent of ")+ 
  labs(fill = "Round")+
  ggtitle("Plot")+
  scale_fill_brewer(palette = "Set1") +
  theme_light(base_size = 16) +
  theme(plot.title = element_text(hjust = 0.5))

How to drop x value from ggplot with discrete axis?

You just subset the names when you pass in the limits:

ggplot(df, aes(names, values))+
  geom_bar(stat = "identity")+
  scale_x_discrete(limits = names[values>0])

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