Modify Column Merging

Merge two or more columns in a gtsummary table. Use show_header_names() to print underlying column names.

modify_column_merge(x, pattern, rows = NULL)

Arguments

x

gtsummary object

pattern

glue syntax string indicating how to merge columns in x$table_body. For example, to construct a confidence interval use "{conf.low}, {conf.high}".

rows

predicate expression to select rows in x$table_body. Can be used to style footnote, formatting functions, missing symbols, and text formatting. Default is NULL. See details below.

Value

gtsummary table

Details

1. Calling this function merely records the instructions to merge columns. The actual merging occurs when the gtsummary table is printed or converted with a function like as_gt().

2. Because the column merging is delayed, it is recommended to perform major modifications to the table, such as those with tbl_merge() and tbl_stack(), before assigning merging instructions. Otherwise, unexpected formatting may occur in the final table.

3. If this functionality is used in conjunction with tbl_stack() (which includes tbl_uvregression()), there is potential issue with printing. When columns are stack AND when the column-merging is defined with a quosure, you may run into issues due to the loss of the environment when 2 or more quosures are combined. If the expression version of the quosure is the same as the quosure (i.e. no evaluated objects), there should be no issues. Regardless, this argument is used internally with care, and it is not recommended for users.

Future Updates

There are planned updates to the implementation of this function with respect to the pattern= argument. Currently, this function replaces a numeric column with a formatted character column following pattern=. Once gt::cols_merge() gains the rows= argument the implementation will be updated to use it, which will keep numeric columns numeric. For the vast majority of users, the planned change will be go unnoticed.

If this functionality is used in conjunction with tbl_stack() (which includes tbl_uvregression()), there is potential issue with printing. When columns are stack AND when the column-merging is defined with a quosure, you may run into issues due to the loss of the environment when 2 or more quosures are combined. If the expression version of the quosure is the same as the quosure (i.e. no evaluated objects), there should be no issues. Regardless, this argument is used internally with care, and it is not recommended for users.

Example Output

Example 1

Example 2

See also

Other Advanced modifiers: modify_column_alignment(), modify_column_hide(), modify_column_indent(), modify_fmt_fun(), modify_table_body(), modify_table_styling()

Examples

# \donttest{
# Example 1 ----------------------------------
modify_column_merge_ex1 <-
  trial %>%
  select(age, marker, trt) %>%
  tbl_summary(by = trt, missing = "no") %>%
  add_p(all_continuous() ~ "t.test",
    pvalue_fun = ~ style_pvalue(., prepend_p = TRUE)
  ) %>%
  modify_fmt_fun(statistic ~ style_sigfig) %>%
  modify_column_merge(pattern = "t = {statistic}; {p.value}") %>%
  modify_header(statistic ~ "**t-test**")

# Example 2 ----------------------------------
modify_column_merge_ex2 <-
  lm(marker ~ age + grade, trial) %>%
  tbl_regression() %>%
  modify_column_merge(
    pattern = "{estimate} ({ci})",
    rows = !is.na(estimate)
  )
# }