Adding continuous tabulating function

[ddsjoberg]

What changes are proposed in this pull request?

• Added new function tbl_continuous() to summarize a continuous variable by 1 or more categorial variables.
• Added tbl_strata(.stack_group_header=) argument to include/exclude the headers when tables are combined with tbl_stack()
• Added tbl_strata(.quiet=) argument.

If there is an GitHub issue associated with this pull request, please provide link.

# Example 1 ----------------------------------
tbl_continuous_ex1 <-
  tbl_continuous(
    data = trial,
    variable = age,
    by = trt,
    include = grade
  )

# Example 2 ----------------------------------
tbl_continuous_ex2 <-
  tbl_continuous(
    data = trial,
    variable = age,
    include = c(trt, grade)
  )

---

Checklist for PR reviewer

• PR branch has pulled the most recent updates from master branch. Ensure the pull request branch and your local version match and both have the latest updates from the master branch.
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When the branch is ready to be merged into master:

• Update NEWS.md with the changes from this pull request under the heading "# gtsummary (development version)". If there is an issue associated with the pull request, reference it in parantheses at the end update (see NEWS.md for examples).
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• Approve Pull Request
• Merge the PR. Please use "Squash and merge".

[karissawhiting]

@ddsjoberg This feature is really useful. I'm looking forward to using it!

An initial thought about the statistic argument:

I was thinking it would be useful to accept a list of formulas and allow different continuous statistic types for different comparison variables.

E.g.

tbl_continuous(
  data = trial,
  variable = age,
  statistic =  list(grade ~ "{mean}", 
                    trt ~ "{median}"),
  include = c(trt, grade)
)

However, using it this way is a llittle inconsistent with left side variable ~ right side statistic relationship in tbl_summary(), so that could potentially be confusing?

Conversely, you could acheive the same result this way:

x <- tbl_continuous(
  data = trial,
  variable = age,
  statistic =  "{mean}",
  include = c(grade)
)

y <- tbl_continuous(
  data = trial,
  variable = age,
  statistic =  "{median}",
  include = c(trt)
)

tbl_stack(list(x, y))

But it's a bit more cumbersome and the footnote needs adjustment.

Thoughts on this?

Also, is there a way to use continuous2 for multi-line continuous stats here? Could it potentially default to this if the user passes a vector of length 2 to statistic argument (e.g. statistic = c("{median} ({p25}, {p75})", "{min}, {max}")?

[ddsjoberg]

Thank you for the review @karissawhiting !!

You make a very good point, and this is something I planned very poorly unfortunately. The tbl_summary(statistic=) argument take a formula list, tbl_cross(statistic=) is a string, and it's not consistent. UGH

Since tbl_summary() is more often used, matching that syntax is preferable I think. I"ll see how difficult that update is, and report back!

[larmarange]

Just a quick comment, but it is also possible to replicate tbl_continuous() with the drafted tbl_custom_summary() who already accepts different statistics per variable.

cf. #976 (comment)

;-)

[ddsjoberg]

FYI @larmarange @karissawhiting I am going to update this function to use Joseph's contribution tbl_custom_summary(): it'll make the internals sooo much nicer to read :)

[ddsjoberg]

Hey @karissawhiting @larmarange !

I updated the back-end to use tbl_custom_summary().....so much less code! Very nice! Thanks @larmarange !

this allows users to select different stats for variable variables and I also added a digits argument to control rounding of the continuous variable.

[larmarange]

That's great @ddsjoberg

• Would it be relevant to add the option overall_row? Could be useful here.
• Just curious, why duplicating continuous_summary ()

[ddsjoberg]

@larmarange

Just curious, why duplicating continuous_summary()

I forgot there was a copy already in the package 😆