Grouped geom_bar with some "0" values

[jmnp]

Hi,

Let's imagine that Nicol, Steve, Mary are chatting on a Whatsapp private group in 2020. In 2021, Frank joins the group.

I would like to visualise the number of messages each one has written each year.

Here is the code:

year <- factor(c(rep(c(2020), 11), rep(c(2021), 8)))
author <- c("Mary", "Nicol", "Steve", "Mary", "Nicol", "Mary", "Mary", "Mary", "Steve", "Nicol", "Mary",
            "Nicol", "Steve", "Frank", "Mary", "Mary", "Frank", "Nicol", "Nicol")
msg <- rep("blablabla", 19)
df <- data.frame(year, author, msg)

p <- ggplot(df, aes(x = author, group = year, fill = year))
p + geom_bar(position = "dodge2")
  labs(x = "", y = "Number of messages", title = "Number of messages by year and by author")

The result is shown here:

There is a problem with Frank: I would like to find a simple way to reduce the width of Frank's bar, so that 2020 remains as = 0.

Thanks,
Cheers

[JackDavison]

So there are a couple of ways to approach this:

Preserve Single

library(tidyverse)

year <- factor(c(rep(c(2020), 11), rep(c(2021), 8)))
author <- c("Mary", "Nicol", "Steve", "Mary", "Nicol", "Mary", "Mary", "Mary", "Steve", "Nicol", "Mary",
            "Nicol", "Steve", "Frank", "Mary", "Mary", "Frank", "Nicol", "Nicol")
msg <- rep("blablabla", 19)
df <- data.frame(year, author, msg)

p <- ggplot(df, aes(x = author, group = year, fill = year))
p + geom_bar(position = position_dodge2(preserve = "single")) +
  labs(x = "", y = "Number of messages", title = "Number of messages by year and by author")

tidyr::complete

library(tidyverse)

year <- factor(c(rep(c(2020), 11), rep(c(2021), 8)))
author <- c("Mary", "Nicol", "Steve", "Mary", "Nicol", "Mary", "Mary", "Mary", "Steve", "Nicol", "Mary",
            "Nicol", "Steve", "Frank", "Mary", "Mary", "Frank", "Nicol", "Nicol")
msg <- rep("blablabla", 19)
df <- data.frame(year, author, msg)

df |> 
  count(year, author) |> 
  complete(year, author) |> 
  ggplot(aes(x = author, y = n, fill = year)) +
  geom_col(position = position_dodge2()) +
  labs(x = "", y = "Number of messages", title = "Number of messages by year and by author")
#> Warning: Removed 1 rows containing missing values (geom_col).

^{Created on 2021-12-08 by the reprex package (v2.0.1)}