r - Left-adjust title in ggplot2, or absolute position for ggtitle

Question

I would like to left align the title in a plot like this

ggplot(data = economics, aes(x = date, y = unemploy)) +
 geom_line() +
 ggtitle("Unemployment in USA between 1967 and 2007") +
 xlab("") +
 ylab("Unemployed [thousands]")

First attempt

ggplot(data = economics, aes(x = date, y = unemploy)) + geom_line() +
 ggtitle("Unemployment in USA for some years") +
 xlab("") +
 ylab("Unemployed [thousands]") +
 theme(plot.title = element_text(hjust = -0.45, vjust=2.12)))

Yay success! But wait... there's more... now I want to change the title to something else.

ggplot(data = economics, aes(x = date, y = unemploy)) +
 geom_line() +
 ggtitle("Unemployment in USA between 1967 and 2007") +
 xlab("") +
 ylab("Unemployed [thousands]") +
 theme(plot.title = element_text(hjust = -0.45, vjust=2.12))

So now I need to adjust hjust... :(

The question

How can I make the title left justified (a couple of pixels left of the y axis label or so) over and over again without messing with the hjust value? Or what is the relationship between hjust and the length of the string?

I have tried to annotate manually according to this question, but then I got only the title, and nothing else for some reason - and an error.

Thank you!

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'

ggplot(data = economics, aes(x = date, y = unemploy)) + 
  geom_line() +
  labs(x=NULL,
       y="Unemployed [thousands]",
       title = "Unemployment in USA for some years",
       subtitle = "A subtitle possibly",
       caption  = "NOTE: Maybe a caption too in italics.") +
  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)}