The `gt` package

The gt package is an excellent way to create and customize nice table output in R. You can read more about this package on its github page. You can install it directly from the CRAN by running the following:

install.packages("gt")

Default gt table

Tables from gt are sober but highly customizable

library(gt)
library(dplyr)

# dataset
data = data.frame(
  Planet = c("Earth", "Mars", "Jupiter", "Venus"),
  Moons = c(1, 2, 79, 0),
  Distance_from_Sun = c(149.6, 227.9, 778.3, 108.2),
  Diameter = c(12742, 6779, 139822, 12104)
)

# create and display the gt table (equivalent to "gt(data)")
data %>%
  gt()

Planet	Moons	Distance_from_Sun	Diameter
Earth	1	149.6	12742
Mars	2	227.9	6779
Jupiter	79	778.3	139822
Venus	0	108.2	12104

Add a simple footer in markdown

The most practical and intuitive way to create a gt table is to use it in combination of the dplyr package.

Thanks to the tab_footnote() function, we can super easily add a footer. And with the md() function we can write it in markdown.

library(gt)
library(dplyr)

# create and display the gt table 
data %>%
  gt() %>%
    tab_footnote(footnote = md("This text is the footer of this **table**"))

Planet	Moons	Distance_from_Sun	Diameter
Earth	1	149.6	12742
Mars	2	227.9	6779
Jupiter	79	778.3	139822
Venus	0	108.2	12104
This text is the footer of this table

Footer with reference

If your footer is intended to refer to a table element, you can add the location argument to specify which part of the table your footnote refers to.

library(gt)
library(dplyr)

# create and display the gt table 
data %>%
  gt() %>%
    tab_footnote(footnote = md("Measured in **millions** of Km"),
                 locations = cells_column_labels(columns = Distance_from_Sun))

Planet	Moons	Distance_from_Sun¹	Diameter
Earth	1	149.6	12742
Mars	2	227.9	6779
Jupiter	79	778.3	139822
Venus	0	108.2	12104
¹ Measured in millions of Km

Footer with mutliple references

Adding multiple references is just as easy as adding one: just add as much as you need the tab_footnote() function

library(gt)
library(dplyr)

# create and display the gt table 
data %>%
  gt() %>%
    tab_footnote(footnote = md("Measured in **millions** of Km"),
                 locations = cells_column_labels(columns = Distance_from_Sun)) %>%
    tab_footnote(footnote = md("Measured in **Km**"),
                 locations = cells_column_labels(columns = Diameter))

Planet	Moons	Distance_from_Sun¹	Diameter²
Earth	1	149.6	12742
Mars	2	227.9	6779
Jupiter	79	778.3	139822
Venus	0	108.2	12104
¹ Measured in millions of Km
² Measured in Km

Change the type of element that indicates the reference

In this example, we now indicate the footer with letters (in upper case) thanks to the opt_footnote_marks() function.

library(gt)
library(dplyr)

# create and display the gt table 
data %>%
  gt() %>%
    tab_footnote(footnote = md("Measured in **millions** of Km"),
                 locations = cells_column_labels(columns = Distance_from_Sun)) %>%
    tab_footnote(footnote = md("Measured in **Km**"),
                 locations = cells_column_labels(columns = Diameter)) %>%
    tab_footnote(footnote = md("The original data are from *Some Organization*")) %>%
    opt_footnote_marks(marks = "LETTERS")

Planet	Moons	Distance_from_Sun^A	Diameter^B
Earth	1	149.6	12742
Mars	2	227.9	6779
Jupiter	79	778.3	139822
Venus	0	108.2	12104
The original data are from Some Organization
^A Measured in millions of Km
^B Measured in Km

Conclusion

We now know how to customize your table footer with the gt package. There is much more you can do using this package, so feel free to visit the gt table section of the gallery to learn more about it and check other examples.

Customize your footer in your gt tables