Center Plot Title in Ggplot2

Center Plot title in ggplot2

From the release news of ggplot 2.2.0: "The main plot title is now left-aligned to better work better with a subtitle". See also the plot.title argument in ?theme: "left-aligned by default".

As pointed out by @J_F, you may add theme(plot.title = element_text(hjust = 0.5)) to center the title.

ggplot() +
  ggtitle("Default in 2.2.0 is left-aligned")

ggplot() +
  ggtitle("Use theme(plot.title = element_text(hjust = 0.5)) to center") +
  theme(plot.title = element_text(hjust = 0.5))

How to center ggplot plot title

Alternately, you can use gridExtra::grid.arrange and grid::textGrob to create the title without needing to pad it visually. This basically creates a separate plot object with your title and glues it on top, independing of the contents of your ggplot call.

First store your whole ggplot call in a variable, e.g. p1:

grid.arrange(textGrob("Mary Poppins", 
               gp = gpar(fontsize = 2.5*11, fontface = "bold")), 
             p1, 
             heights = c(0.1, 1))

You have to translate your theme() settings to gpar(). The base size of theme_light is 11, which is where the 2.5*11 comes from (and the 2.5 from your rel(2.5)).

The advantage here is that you know your title will be truly centered, not just close enough by eye.

Center Plot title in ggplot2 using theme_bw

You just need to invert theme_bw and theme

ggplot(data=dat, aes(x=time, y=total_bill, fill=time)) + 
  geom_bar(colour="black", fill="#DD8888", width=.8, stat="identity") + 
  guides(fill=FALSE) +
  xlab("Time of day") + ylab("Total bill") +
  ggtitle("Average bill for 2 people") +
  theme_bw() +
  theme(plot.title = element_text(hjust = 0.5))

Center align ggplot title when title is placed within the plot area

theme(plot.title = element_text(hjust = 0.5, margin = margin(t=10,b=-20)))

ggplot - centre plot title with total width of image

To my knowledge, this is not possible without manually manipulating grobs, which will be a lot of tinkering. A simple workaround is to make a title "figure" and print it above the actual figure. The gridExtra package makes this easy (but see also patchwork). For instance,

## Start matter ------------------------------------------------------

library(dplyr)
library(ggplot2)
library(gridExtra)

## Data --------------------------------------------------------------

data(mtcars)

mtcars <-
  mtcars %>%
  mutate_at(vars(cyl, carb), factor)

averages_carb <-
  mtcars %>%
  group_by(carb) %>%
  summarise(mpg = mean(mpg)) %>%
  ungroup()

averages_carb_cyl <-
  mtcars %>%
  group_by(carb, cyl) %>%
  summarise(mpg = mean(mpg)) %>%
  ungroup()

## Figure 1 ----------------------------------------------------------

fig_1_title <-
  ggplot() +
  ggtitle("No legend - regular y-text") +
  geom_point() +
  theme_void() +
  theme(plot.title = element_text(size = 20, hjust = .5))

fig_1_main <-
  averages_carb %>%
  ggplot(aes(x = carb, y = mpg)) +
  geom_bar(stat = "identity") +
  scale_y_continuous(
    breaks = 1:25,
    labels = c("Low MPG", rep("", 23), "High MPG")) +
  theme_minimal()

png(
  "No legend - regular y-text.png",
  width = 1000, height = 693, res = 120
)

grid.arrange(
  fig_1_title, fig_1_main,
  ncol = 1, heights = c(1/20, 19/20)
)

dev.off()

## Figure 2 ---------------------------------------------------------

fig_2_title <-
  ggplot() +
  geom_point() +
  ggtitle("Legend - regular y-text") +
  theme_void() +
  theme(plot.title = element_text(size = 20, hjust = .5))

fig_2_main <-
  averages_carb_cyl %>%
  ggplot(aes(x = carb, y = mpg, fill = cyl)) +
  geom_bar(stat = "identity", position = "dodge") +
  scale_y_continuous(
    breaks = 1:28,
    labels = c("Low MPG", rep("", 26), "High MPG")) +
  theme_minimal()

png(
  "Legend - regular y-text.png",
  width = 1000, height = 693, res = 120
)

grid.arrange(
  fig_2_title, fig_2_main,
  ncol = 1, heights = c(1/20, 19/20)
)

dev.off()

## END ---------------------------------------------------------------

(Yes, their centers are aligned.)

Center tags of nested plot using ggplot and patchwork

I was able to get it working with cowplot as an addition

library(ggplot2)
library(patchwork)
library(cowplot)

p1 <- ggplot(mtcars) + 
  geom_point(aes(mpg, disp)) + 
  ggtitle(label = "",
          subtitle = 'Plot 1') 

p2 <- ggplot(mtcars) + 
  geom_point(aes(mpg, disp)) + 
  ggtitle(label = "",
          subtitle = 'Plot 1')

p3 <- ggplot(mtcars) + 
  geom_boxplot(aes(gear, disp, group = gear)) + 
  ggtitle(label = "",
          subtitle = 'Plot 2')

p4 <- ggplot(mtcars) + 
  geom_point(aes(hp, wt, colour = mpg)) + 
  ggtitle(label = "",
          subtitle = 'Plot 3') +
  theme(legend.position = "none")

p5 <- ggplot(mtcars) + 
  geom_bar(aes(gear)) + 
  facet_wrap(~cyl) + 
  ggtitle(label = "",
          subtitle = 'Plot 4')

ptop <- p1 +  plot_annotation("(a) Panel a")& theme(plot.title = element_text(hjust = 0.5))
pbot <- p2 + p3 + p4 + p5 +  plot_annotation("(b) Panel b") & theme(plot.title = element_text(hjust = 0.5))
legend_b <- get_legend(
  p4+
  theme(legend.position = "bottom",
        legend.direction = "horizontal")
)

plot_grid(ptop, pbot, legend_b, ncol = 1, nrow = 3, rel_heights = c(1, 1,0.25))

Center the plot title in ggsurvplot

One relatively easy solution is to define your own custom theme based off of the theme that is used in ggsurvplot(). Looking at the documentation for the function shows us that it is applying via ggtheme= the theme theme_survminer(). We can create a custom function that uses %+replace% to overwrite one of the theme elements of interest from theme_survminer():

custom_theme <- function() {
  theme_survminer() %+replace%
    theme(
      plot.title=element_text(hjust=0.5)
    )
}

Then, you can use that theme by association with the ggtheme= argument of ggsurvplot():

library(ggplot2)
library(survminer)

require("survival")
fit<- survfit(Surv(time, status) ~ sex, data = lung)
ggsurvplot(fit, data = lung, title='Awesome Plot Title', ggtheme=custom_theme())

Center titles and subtitles nd in theme_minimal()

Your guess is correct and adding theme_minimal after you specify a theme overrides the settings. Thus, you need to change the order of your ggplot-call.

ggplot(cars, aes(x = speed)) + 
  geom_bar() +
  labs(title = "speed", subtitle = "other info") +
  theme_minimal() +
  theme(plot.title = element_text(hjust = 0.5),
        plot.subtitle = element_text(hjust = 0.5))

This comes from the layering in ggplot, you can also see this, when you specify e.g. a color scale twice, then you get a warning, saying that the first one will be overwritten. Also your plot show does values on top which are plotted last when you plot several layers (i.e. several geom_point-calls).

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