Header and Footer

The Table Header and Table Footer are bookend components that provide context for the data presented in your table. The header introduces the table with a title and optional subtitle, while the footer anchors it with source notes or other supplementary information. Both are added using the tab_*() family of methods.

Adding a Table Header

The way that we add components like the Table Header and source notes in the Table Footer is to use the tab_*() family of methods. A Table Header is easy to add so let’s see how the previous table looks with a title and a subtitle. We can add this component using the tab_header() method:

from great_tables import GT, md, html
from great_tables.data import islands

islands_mini = islands.head(10)

# Make a display table with the `islands_tbl` table;
# put a heading just above the column labels
(
    GT(islands_mini)
    .tab_header(
        title = "Large Landmasses of the World",
        subtitle = "The top ten largest are presented"
    )
)

name	size
Large Landmasses of the World
The top ten largest are presented
Africa	11506
Antarctica	5500
Asia	16988
Australia	2968
Axel Heiberg	16
Baffin	184
Banks	23
Borneo	280
Britain	84
Celebes	73

The Header table component provides an opportunity to describe the data that’s presented. Using subtitle= allows us to insert a subtitle, which is an optional part of the Header. We may also style the title= and subtitle= using Markdown! We do this by wrapping the values passed to title= or subtitle= with the md() helper function (we may also use html() in a similar fashion). Here is an example with the table data truncated for brevity:

# Make a display table with the `islands_tbl` table;
# put a heading just above the column labels
gt_tbl = (
    GT(islands.head(2))
    .tab_header(
        title = md("Large Landmasses of the *World* &#x1F310;"),
        subtitle = md("The top **ten** largest are presented")
    )
)

gt_tbl

name	size
Large Landmasses of the World 🌐
The top ten largest are presented
Africa	11506
Antarctica	5500

A source note can be added to the table’s Footer through use of the tab_source_note() method. It works in the same way as tab_header() (it also allows for Markdown inputs) except it can be called multiple times—each invocation results in the addition of a source note.

Adding Source Notes

# Display the `islands_tbl` data with a heading and two source notes
(
    gt_tbl
    .tab_source_note(
        source_note = "Source: The World Almanac and Book of Facts, 1975, page 406."
    )
    .tab_source_note(
        source_note = md("Reference: McNeil, D. R. (1977) *Interactive Data Analysis*. Wiley.")
    )
)

name	size
Large Landmasses of the World 🌐
The top ten largest are presented
Africa	11506
Antarctica	5500
Source: The World Almanac and Book of Facts, 1975, page 406.
Reference: McNeil, D. R. (1977) Interactive Data Analysis. Wiley.

With just a few method calls, we have added essential context to the table. The title and subtitle tell the reader what data is being presented, and the source notes provide attribution. Together, these components frame the table body and help your audience understand the data at a glance.