I'm using gglplot2 for creating graphics.

According to the user manual of facet_grid the switch parameter does the following :

switch: By default, the labels are displayed on the top and right of the plot. If '"x"', the top labels will be displayed to the bottom. If '"y"', the right-hand side labels will be displayed to the left. Can also be set to '"both"'.

I would like to know whether it is possible that in a facet using two variables for grouping values, put both variables on bottom, that is below the labels of the x axis. I mean instead of

 
                                2
                                0
                                2
                                2
              march

Is it possible to have

 
                             
                             
                             
                             
              march
              2022

This is actually how I often create bar charts in Excel/Calc and I find it to be much more readable.

Here is my test case :

Dataframe to be used for the graphic

df_graph_data <- data.frame(
    year = rep.int(rep.int("2022", times = 28), times = 4),
    month = rep.int(rep.int("march", times = 28), times = 4),
    day_number = rep.int(seq_len(28), times = 4),
    user_name = rep.int(
        c(
            rep.int("all users", times = 28),
            rep.int("user1", times = 28),
            rep.int("user2", times = 28),
            rep.int("user3", times = 28)
        ),
        times = 4
    ),
    nbr_requetes = c(
        3756702L, 2147114L, 3931021L, 3250020L,
        2902070L, 1807425L, 2793984L, 2923112L,
        3240588L, 2965146L, 2778786L, 1915146L,
        1945332L, 2763420L, 2948967L, 2953477L,
        3056854L, 3005814L, 2252867L, 2503640L,
        2574102L, 1525419L, 1694105L, 2796715L,
        2448590L, 1571465L, 1641066L, 2406683L,
        358992L, 294093L, 264117L, 164634L,
        132962L, 147587L, 211403L, 187508L,
        249445L, 309832L, 295148L, 114369L,
        178935L, 229215L, 108168L, 202477L,
        268470L, 301246L, 199027L, 281434L,
        216888L, 135288L, 196308L, 219157L,
        111560L, 73738L, 112145L, 177282L,
        349976L, 146039L, 404627L, 443312L,
        298097L, 294996L, 317332L, 389586L,
        308677L, 313986L, 300024L, 309731L,
        270230L, 310996L, 355700L, 312721L,
        371876L, 303862L, 293709L, 275199L,
        287980L, 148739L, 172012L, 363912L,
        300369L, 299126L, 280704L, 326646L,
        642780L, 350965L, 633404L, 432376L,
        119252L, 109750L, 519688L, 546885L,
        507847L, 489425L, 460825L, 168577L,
        163430L, 505327L, 515003L, 498683L,
        492875L, 441591L, 198819L, 188225L,
        513477L, 390207L, 400769L, 493959L,
        458977L, 166925L, 151197L, 558081L
    )
)
df_graph_data$user_name <- factor(df_graph_data$user_name, ordered = TRUE, levels = c("all users", "user1", "user2", "user3"))

Code for the graphic

library("tidyverse")
options(device = "windows")
###
###
require(scales)
ggplot(data = df_graph_data)   
  geom_bar(mapping = aes(
    x = day_number,
    y = nbr_requetes,
    fill = user_name
  ), 
  position = "dodge",
  stat = "identity"
  )  
  scale_x_continuous(
    breaks=seq(
      min(df_graph_data$day_number), 
      max(df_graph_data$day_number), 
      by = 1L),
    labels = stringr::str_pad(
      unique(df_graph_data$day_number), 
      width = 2, 
      pad = "0"
    )
  )   
  scale_y_continuous(
    limits = c(0, 4000000),
    labels = comma,
    expand = expansion(mult = 0, add = 0)
  )   
  facet_grid(
    rows = vars(year),
    cols = vars(month),
    switch = "x",
    scales = "free_x",
    space = "free_x"
  )  
  labs(
    x = "day number",
    y = "query count per day",
    caption = "Test API"
  )  
  ggtitle("March 2022 : Active users")  
  theme(
    strip.placement = "outside",
    axis.text.x = element_text(angle = 0, vjust = 0.5, hjust=0.5),
    axis.title.y = element_text(margin = margin(t = 0, r = 15, b = 0, l = 0)),
    axis.title.x = element_text(margin = margin(t = 15, r = 0, b = 0, l = 0)),
    plot.title = element_text(hjust = 0.5, size = 12),
    plot.caption = element_text(size = 8, hjust = 1),
    plot.caption.position = "plot",
    panel.spacing.x=unit(0.0, "lines"),
    panel.spacing.y=unit(0.0, "lines")
  )  
  guides(fill=guide_legend(title="User account"))   
  scale_fill_manual(values = c("all users" = "#004586",
                               "user1" = "#ffd320",
                               "user2" = "#579d1c",
                               "user3" = "#7e0021"))

In the above graphics the year 2022 is on the top right hand side. Is there any way to put below the month value (march)?

CodePudding user response：

You can change to facet_wrap(), with strip.position = "bottom" indicated, like this:

  facet_wrap(~year month,
    strip.position = "bottom",
    scales = "free_x"
  )

CodePudding user response：

If you want to keep facet_grid functionality, you could also use ggh4x::facet_nested

(note I've stripped your plot from lots of extraneous bits)

library(tidyverse)

## ...preparing your data, as per your question... 

ggplot(data = df_graph_data)  
  geom_col(mapping = aes(
    x = day_number,
    y = nbr_requetes,
    fill = user_name
  ))  
  ggh4x::facet_nested(~year month,
    switch = "x",
    scales = "free_x",
    space = "free_x"
  )  
  theme(
    strip.placement = "outside"
  )