rkableextra

kableExtra::add_header_above leaves empty header cells unstyled

I'm using the kableExtra package in R to create a table with styled headers, but I’m having trouble applying the same background color to header cells that are blank. When I use add_header_above with empty placeholders, they default to white, while non-empty placeholders in add_header_abovereceive the specified background color.

enter image description here

Here's an example of my code:

library(kableExtra)

# Sample data
results_df <- data.frame(
  visit = c("Visit 1", "Visit 2", "Visit 3"),
  n = c(100, 95, 90),
  raw_mean = c(10.2, 9.8, 8.7),
  raw_ci_lower = c(9.5, 9.1, 8.0),
  raw_ci_upper = c(10.9, 10.5, 9.4),
  adjusted_mean = c(10.0, 9.6, 8.5),
  adj_ci_lower = c(9.3, 8.9, 7.8),
  adj_ci_upper = c(10.7, 10.3, 9.2),
  adjustment_warning = c("None", "High variance", "None")
)

# Generate table
results_df %>%
  kable("html", col.names = c("Visit", "N", "Raw Mean", "Raw CI Lower", "Raw CI Upper",
                              "Adjusted Mean", "Adj. CI Lower", "Adj. CI Upper", "Warning")) %>%
  kable_styling(bootstrap_options = c("striped"), 
                font_size = 16, 
                full_width = TRUE, 
                position = "center") %>%
  add_header_above(c("&nbsp;" = 2, "Raw Data" = 3, "Adjusted Data" = 3, "&nbsp;" = 1), 
                   background = "#1482FA", color = "#FFFFFF") %>%
  row_spec(0, bold = TRUE, background = "#1482FA", color = "#FFFFFF")

Any idea how I can fix that?

Solution

  • One option or workaround would be to use some placeholder text for which you set the color= to "transparent":

    library(kableExtra)

# Sample data
results_df <- data.frame(
  visit = c("Visit 1", "Visit 2", "Visit 3"),
  n = c(100, 95, 90),
  raw_mean = c(10.2, 9.8, 8.7),
  raw_ci_lower = c(9.5, 9.1, 8.0),
  raw_ci_upper = c(10.9, 10.5, 9.4),
  adjusted_mean = c(10.0, 9.6, 8.5),
  adj_ci_lower = c(9.3, 8.9, 7.8),
  adj_ci_upper = c(10.7, 10.3, 9.2),
  adjustment_warning = c("None", "High variance", "None")
)

# Generate table
results_df %>%
  kable("html",
    col.names = c(
      "Visit", "N", "Raw Mean", "Raw CI Lower", "Raw CI Upper",
      "Adjusted Mean", "Adj. CI Lower", "Adj. CI Upper", "Warning"
    )
  ) %>%
  kable_styling(
    bootstrap_options = c("striped"),
    font_size = 16,
    full_width = TRUE,
    position = "center"
  ) %>%
  add_header_above(c("Foo" = 2, "Raw Data" = 3, "Adjusted Data" = 3, "Foo" = 1),
    background = "#1482FA",
    color = c("transparent", "#FFFFFF", "#FFFFFF", "transparent")
  ) %>%
  row_spec(0, bold = TRUE, background = "#1482FA", color = "#FFFFFF")

    enter image description here