How do you format multiple columns under the same spanner? / How does gt() assign column location?

Question

I have a gt table that has a series of spanners. Each spanner has two columns beneath it. I'd like to format it such that the columns under every other spanner are highlighted. Columns 1 has the stub values. In the code below, column 2 is the location of the first column under Spanner 1. I would expect column 3 to highlight the column directly next to 2, but instead it skips that column and highlights the first column of the second spanner (what I would call column 4).

my_data %>%
 gt() %>%
 tab_spanner_delim(delim = "_") %>%    
 tab_style(
       style = list(cell_fill(color = "#f2dddc")),
       locations = cells_body(columns = c(2,3)) # 6,7,10,11, etc. for every other spanner
           )

So how do I format my code to reference both columns under a spanner/how do I reference any column under a spanner that isn't the first column? Is there a way to reference the spanner as the location reference?

And for what it's worth, I'm doing this within Shiny, so once I understand the mechanics of gt() I will need to further modify the code to make it dynamic.

Thank you!

Update: I'm having similar issues with referencing spanners. The code below successfully adds a left border starting from the spanner and running to the bottom of the column on columns 2 and 3 (so the first spanner and its 2 columns are wrapped in outer borders).

%>%
        tab_style(
          style = list(cell_borders(
            sides = "left",
            color = "black",
            weight = px(3)
          )),
          locations = list(cells_column_labels(columns = c(2,3)), #left side of column two and 3 (remember col 3 is the first column of spanner 2)
                           cells_body(columns = c(2,3)), #Repeat of above but with the column values
                           cells_column_spanners(spanners = c(1,2)) #Left sides of spanners 1 and 2 (left side of spanner 2 = left side of col 3)
        )) #Results are as expected

Now, I want to highlight the name of the first spanner. Given the code chunk above, it makes sense to me to reference spanner 1. When I reference spanner 1, the second spanner is highlighted. Any idea why? I don't understand why I can get a border to the left of spanner 1 by referencing '1', but when I make the same spanner reference to highlight the cell, it highlights spanner 2. I then tried referencing spanner 0 and it threw an error that the indice didn't exist.

%>%
     tab_style(
      style = list(
         cell_fill(color = "#f2dddc")),
       locations = list(cells_column_spanners(
         spanners = 1)) #Why does this line highlight spanner 2?
              )

mlpost mlpost · Accepted Answer · 2021-08-05T16:38:17

I've come to realize that the (my) confusion lies in the tab spanner delimiter. I used pivot_wider to prepare my data for gt() resulting in a df formatted as such: (1) Group1_varA, (2) Group2_varA, (3) Group3_varA, (4) Group1_varB, (5) Group2_varB, (6) Group2_varB.

The tab_spanner_delimiter rearranges the columns so varA and VarB are under their respective groups, but the column indices don't change, making the column orders in the above example 1,4,2,5,3,6.

How do you format multiple columns under the same spanner? / How does gt() assign column location?

1 Answers