Aligning title, subtitle and caption for horizontal ggplot barchart

Question

I would like to left align the plot.title, plot.subtitle and plot.caption in a horizontal ggplot2 barchart.

Example:

Answer 1

This question refers to this github tidyverse/ggplot2 solved issue: https://github.com/tidyverse/ggplot2/issues/3252

And it is implemented in ggplot2 (development version): https://github.com/tidyverse/ggplot2/blob/15263f7580d6b5100989f7c1da5d2f5255e480f9/NEWS.md

Themes have gained two new parameters, plot.title.position and plot.caption.position, that can be used to customize how plot title/subtitle and plot caption are positioned relative to the overall plot (@clauswilke, #3252).

To follow your example as a reprex:

# First install the development version from GitHub:
#install.packages("devtools") #If required
#devtools::install_github("tidyverse/ggplot2")

library(ggplot2)
packageVersion("ggplot2")
#> [1] '3.2.1.9000'

df <- data.frame(type=factor(c("Brooklyn","Manhatten and\n Queens")),
                 value=c(15,30))

ggplot(df, aes(x=type, y=value)) +
  geom_bar(stat='identity') +
  coord_flip() +
  labs(title = "This is a nice title",
       subtitle = "A subtitle",
       caption  = "We even have a caption. A very long one indeed.") +
  theme(plot.caption = element_text(hjust = 0, face= "italic"), #Default is hjust=1
        plot.title.position = "plot", #NEW parameter. Apply for subtitle too.
        plot.caption.position =  "plot") #NEW parameter

^{Created on 2019-09-04 by the reprex package (v0.3.0)}