How To Remove facet_wrap Title Box in ggplot2?

Remove title box in facet_wrap() in ggplot2
Remove title box in facet_wrap() in ggplot2

In this tutorial, we will see how to remove box surrounding title of each facets made with facet_wrap() function in ggplot2.

Let us load tidyverse and set ggplot2 theme_bw() with base size 16. Let us use Palmer penguin dataset to make plots with facets using facet_wrap() in ggplot2. We ill use the palmerpenguins package to get the data. One can also load Penguins data directly from github page.

library(tidyverse)
library(palmerpenguins)
theme_set(theme_bw(16))

penguins %>% head()

## # A tibble: 6 x 8
##   species island bill_length_mm bill_depth_mm flipper_length_… body_mass_g sex  
##   <fct>   <fct>           <dbl>         <dbl>            <int>       <int> <fct>
## 1 Adelie  Torge…           39.1          18.7              181        3750 male 
## 2 Adelie  Torge…           39.5          17.4              186        3800 fema…
## 3 Adelie  Torge…           40.3          18                195        3250 fema…
## 4 Adelie  Torge…           NA            NA                 NA          NA <NA> 
## 5 Adelie  Torge…           36.7          19.3              193        3450 fema…
## 6 Adelie  Torge…           39.3          20.6              190        3650 male 
## # … with 1 more variable: year <int>

facet_wrap() example with default grey title box

Let us make a scatter plot between Penguin’s bill length vs depth with year as faceting variable. We also add color to species variable

penguins %>% 
  ggplot(aes(x=bill_length_mm, 
             y=bill_depth_mm, 
             color=species))+
  geom_point()+
  geom_smooth(method = "lm")+
  facet_wrap(~year)
ggsave("customize_facet_wrap_ggplot2.png")

By default, ggplot2 creates the values of the faceting variable, in this example year, as title for each facetted plot in grey color box.

Default facet_wrap() plot with title box

removing facet_wrap()’s grey title box

We can customize the facet_wrap() plot by removing the grey box altogether using theme() function. theme() function in ggplot2 is a versatile function to customize the look of a plot made with ggplot2. To remove the grey box, we need to specify “strip.background = element_blank()” as argument to theme() function.

penguins %>%
  ggplot(aes(x=bill_length_mm, 
             y=bill_depth_mm,
             color=species))+
  geom_point()+
  geom_smooth(method = "lm")+
  facet_wrap(~year)+
  theme(strip.background = element_blank())
ggsave("facet_wrap_without_box_ggplot2.png")

Voila, now the default grey box is gone in each facet. And the title for each facet is much simple now.

Remove grey box in facet_wrap() with strip.background in theme()

Do you want to keep the box, but change the default grey color? Check out this post, How To Change facet_wrap() Box Color in ggplot2? to learn how strip.background is useful to change color.

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