Tables"

In visOmopResults: Graphs and Tables for OMOP Results

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Introduction

The visOmopResults package provides user-friendly tools for creating well-formatted tables and plots that are publication-ready. In this vignette, we focus specifically on the table formatting functionalities. The package supports four table formats: <tibble>, <gt>, <flextable>, and <datatables>. While <tibble> is an <data.frame> R object, <gt> and <flextable> are designed to create publication-ready tables that can be exported to different formats (e.g., PNG, Word, PDF, HTML), and <datatables> display tables on HTML pages. These last three can be used in ShinyApps, RMarkdown, Quarto, and more.

Although the primary aim of the package is to simplify the handling of the <summarised_result> class (see omopgenerics for more details), its functionalities can be applied to any <data.frame> if certain requirements are met.

Types of Table Functions

There are two main categories of table functions in the package:

• Main Table Functions: Comprehensive functions like visOmopTable() and visTable() allow users to fully format tables, including specifying headers, grouping columns, and customising styles.

• Additional Table Formatting Functions: The format function set provides more granular control over specific table elements, enabling advanced customisation beyond the main functions.

This vignette will guide you through the usage of these functions.

Main Functions

These functions are built on top of the format functions, providing a quick and straightforward way to format tables.

visTable()

visTable() is a flexible function designed to format any <data.frame>.

Let's demonstrate its usage with a dataset from the palmerpenguins package.

library(visOmopResults)
library(palmerpenguins)
library(dplyr)
library(tidyr)
x <- penguins |> 
  filter(!is.na(sex) & year == 2008) |> 
  select(!"body_mass_g") |>
  summarise(across(ends_with("mm"), ~mean(.x)), .by = c("species", "island", "sex"))
head(x)

We can format this data into a <gt> table using visTable() as follows:

visTable(
  result = x,
  groupColumn = c("sex"),
  rename = c("Bill length (mm)" = "bill_length_mm",
             "Bill depth (mm)" = "bill_depth_mm",
             "Flipper length (mm)" = "flipper_length_mm"),
  type = "gt",
  hide = "year"
)

To use the arguments estimateName and header, the <data.frame> must have the estimates arranged into three columns: estimate_name, estimate_type, and estimate_value. Let's reshape the example dataset accordingly and demonstrate creating a <flextable> object:

# Transforming the dataset to include estimate columns
x <- x |>
  pivot_longer(
    cols = ends_with("_mm"), 
    names_to = "estimate_name", 
    values_to = "estimate_value"
  ) |>
  mutate(estimate_type = "numeric")

# Creating a formatted flextable
visTable(
  result = x,
  estimateName = c(
    "Bill length - Bill depth (mm)" = "<bill_length_mm> - <bill_depth_mm>",
    "Flipper length (mm)" = "<flipper_length_mm>"
  ),
  header = c("species", "island"),
  groupColumn = "sex",
  type = "flextable",
  hide = c("year", "estimate_type")
)

visOmopTable()

visOmopTable() extends the functionality of visTable() with additional features tailored specifically for handling <summarised_result> objects, making it easier to work with standardized result formats.

Let's demonstrate visOmopTable() with a mock <summarised_result>:

# Creating a mock summarised result
result <- mockSummarisedResult() |>
  filter(strata_name == "age_group &&& sex")

# Displaying the first few rows
head(result)

# Creating a formatted gt table
visOmopTable(
  result = result,
  estimateName = c(
    "N%" = "<count> (<percentage>)",
    "N" = "<count>",
    "Mean (SD)" = "<mean> (<sd>)"
  ),
  header = c("package_name", "age_group"),
  groupColumn = c("cohort_name", "sex"),
  settingsColumn = "package_name",
  type = "gt"
)

The workflow is quite similar to visTable(), but it includes specific enhancements for <summarised_result> objects:

• Automatic splitting: The result object is always processed using the splitAll() function. Thereby, column names to use in other arguments must be based on the split result.

• settingsColumn argument: Use this argument to specify which settings should be displayed in the main table. The columns specified here can also be referenced in other arguments such as header, rename, and groupColumn.

• header argument: accepts specific <summarised_result> inputs, in addition to its typical usage as in visTable(). For example, use "strata" in the header to display all variables in strata_name, or use "settings" to show all settings specified in settingsColumns.

• Hidden columns: result_id and estimate_type columns are always hidden as they serve as helper columns for internal processes.

• Suppressed estimates: if the result object has been processed with suppress(), obscured estimates can be displayed as the default na value or as "<{minCellCount}" with the corresponding minimum count value used. This can be controlled using the showMinCellCount argument.

In the next example, visOmopTable() generates a <gt> table while displaying suppressed estimates (those with counts below 1,000,000) with the specified minimum cell count.

result |>
  suppress(minCellCount = 1000000) |>
  visOmopTable(
    estimateName = c(
      "N%" = "<count> (<percentage>)",
      "N" = "<count>",
      "Mean (SD)" = "<mean> (<sd>)"
    ),
    header = c("group"),
    groupColumn = c("strata"),
    hide = c("cdm_name"),
    showMinCellCount = TRUE,
    type = "reactable"
  )

Customise tables

Tables displayed in visOmopResults() follow a default style, but customisation is possible through the style and .options arguments. These allow users to modify various formatting aspects using options from the format functions (see the format Functions section to learn more).

Style

By default, the visOmopResults default style is applied for all tables. At the moment, besides from the default style, the package also supports the "darwin" style (only for gt and flextable).

To inspect the code for the default styles of the different table types supported, you can use the tableStyle() function as showed next. To know more about styling with these options, please refer to each of the table packages.

tableStyle(type = "gt")

tableStyle(type = "flextable")

tableStyle(type = "datatable")

tableStyle(type = "reactable")

Further Options

The main vis table functions are built on top of specific formatting functions described in the next section. These core table functions do not directly expose all customization arguments in their signature. Instead, additional tweaks can be made via the .options argument.

To view the full list of customization options and their default values, use:

tableOptions()

As mentioned, all these arguments originate from specific formatting functions. The table below shows, for each argument, the function it belongs to and its purpose:

bind_rows(
  tibble(
    Function = "formatEstimateValue()",
    Argument = c("decimals", "decimalMark", "bigMark"),
    Description = c(
      "Number of decimals to display, which can be specified per estimate type (integer, numeric, percentage, proportion), per estimate name, or applied to all estimates.",
      "Symbol to use as the decimal separator.",
      "Symbol to use as the thousands and millions separator."
    )
  ),
  tibble(
    Function = "formatEstimateName()",
    Argument = c("keepNotFormatted", "useFormatOrder"),
    Description = c(
      "Whether to retain rows with estimate names that are not explicitly formatted.",
      "Whether to display estimate names in the order provided in `estimateName` (TRUE) or in the order of the input data frame (FALSE)."
    )
  ),
  tibble(
    Function = "formatHeader()",
    Argument = c("delim", "includeHeaderName", "includeHeaderKey"),
    Description = c(
      "Delimiter to use when separating header components.",
      "Whether to include the column name as part of the header.",
      "Whether to prefix header elements with their type (e.g., header, header_name, header_level)."
    )
  ),
  tibble(
    Function = "formatTable()",
    Argument = c("style", "na", "title", "subtitle", "caption", "groupAsColumn", "groupOrder", "merge"),
    Description = c(
      "Named list specifying styles for table components (e.g., title, subtitle, header, body). Use `'default'` for the default `visOmopResults` style or `NULL` for the package default (either `gt` or `flextable`). Use `gtStyle()` or `flextableStyle()` to preview the default styles.",
      "Value to display for missing data.",
      "Title of the table. Use `NULL` for no title.",
      "Subtitle of the table. Use `NULL` for no subtitle.",
      "Caption in markdown format. Use `NULL` for no caption. For example, *Your caption here* renders in italics.",
      "Whether to display group labels as a separate column (`TRUE`) or as row headers (`FALSE`).",
      "Order in which to display group labels.",
      "Columns to merge vertically when consecutive cells have the same value. Use `'all_columns'` to merge all, or `NULL` for no merging."
    )
  )
) |>
  formatTable(groupColumn = "Function")

Formatting Functions

The format set of functions can be used in a pipeline to transform and format a <data.frame> or a <summarised_result> object. Below, we'll demonstrate how to utilize these functions in a step-by-step manner.

1) Format Estimates

The formatEstimateName() and formatEstimateValue() functions enable you to customise the naming and display of estimates in your table.

To illustrate their usage, we'll continue with the result dataset. Let's first take a look at some of the estimates before any formatting is applied:

result |> 
  filterGroup(cohort_name == "cohort1") |>  # visOmopResult filter function
  filterStrata(age_group == "<40", sex == "Female") |>  # visOmopResult filter function
  select(variable_name, variable_level, estimate_name, estimate_type, estimate_value)

1.1) Suppressed estimates

The function formatMinCellCount() indicates which estimates have been suppressed due to the minimum cell count specified in the study.

Estimates are suppressed using omopgenerics::suppress(), which replaces the estimate with the symbol "-". When reporting results, we want to distinguish suppressed estimates from missing values (NA), the formatMinCellCount() function can be used as follows:

result <- result |> formatMinCellCount()

1.2) Estimate values

The formatEstimateValue() function allows you to specify the number of decimals for different estimate_types or estimate_names, as well as customise decimal and thousand separators.

Let's see how the previous estimates are updated afterwars:

# Formatting estimate values
result <- result |>
  formatEstimateValue(
    decimals = c(integer = 0, numeric = 4, percentage = 2),
    decimalMark = ".",
    bigMark = ","
  )

# Displaying the formatted subset
result |> 
  filterGroup(cohort_name == "cohort1") |>  
  filterStrata(age_group == "<40", sex == "Female") |> 
  select(variable_name, variable_level, estimate_name, estimate_type, estimate_value)

As you can see, the estimates now reflect the specified formatting rules.

1.3) Estimate names

Next, we will format the estimate names using the formatEstimateName() function. This function allows us to combine counts and percentages as “N (%)”, among other estimate combinations

# Formatting estimate names
result <- result |> 
  formatEstimateName(
    estimateName = c(
      "N (%)" = "<count> (<percentage>%)", 
      "N" = "<count>",
      "Mean (SD)" = "<mean> (<sd>)"
    ),
    keepNotFormatted = TRUE,
    useFormatOrder = FALSE
  )

# Displaying the formatted subset with new estimate names
result |> 
  filterGroup(cohort_name == "cohort1") |>  
  filterStrata(age_group == "<40", sex == "Female") |> 
  select(variable_name, variable_level, estimate_name, estimate_type, estimate_value)

Now, the estimate names are displayed as specified, such as “N (%)” for counts and percentages. The keepNotFormatted argument ensures that unformatted rows remain in the dataset, while useFormatOrder allows control over the display order of the estimates.

2) Format Header

formatHeader() is used to create complex multi-level headers for tables, making it easy to present grouped data clearly.

Header levels

There are 3 different levels of headers, each identified with the following keys:

• header: Custom labels that do not correspond to column names or table values.

• header_name: Labels derived from column names. Can be omitted with includeHeaderName = FALSE.

• header_level: Labels derived from values within columns set in header.

These keys, together with a delimiter between header levels (delim) are used in formatTable() to format and style gt or flextable tables.

Let's create a multi-level header for the strata columns, including all three keys. This will show how the column names are transformed:

result |>
  mutate(across(c("strata_name", "strata_level"), ~ gsub("&&&", "and", .x))) |>
  formatHeader(
    header = c("Stratifications", "strata_name", "strata_level"),
    delim = "\n",
    includeHeaderName = TRUE,
    includeHeaderKey = TRUE
  ) |> 
  colnames()

For the table we are formatting, we won't include the header_name labels. Let's see how it looks when we exclude them:

result <- result |>
  mutate(across(c("strata_name", "strata_level"), ~ gsub("&&&", "and", .x))) |>
  formatHeader(
    header = c("Stratifications", "strata_name", "strata_level"),
    delim = "\n",
    includeHeaderName = FALSE,
    includeHeaderKey = TRUE
  )  

colnames(result)

3) Format Table

formatTable() function is the final step in the formatting pipeline, where the formatted <data.frame> is converted to either a <gt> or <flextable>.

Prepare data

Before using formatTable(), we'll tidy the <data.frame> by splitting the group and additional name-level columns (see vignette on tidying <summarised_result>), and drop some unwanted columns:

result <- result |>
  splitGroup() |>
  splitAdditional() |>
  select(!c("result_id", "estimate_type", "cdm_name"))
head(result)

Use formatTable()

Now that the data is cleaned and organized, formatTable() can be used to create a well-structured <gt>, <flextable>, datatable, or `reactable`` objects.

result |>
  formatTable(
    type = "gt",
    delim = "\n",
    style = "default",
    na = "-",
    title = "My formatted table!",
    subtitle = "Created with the `visOmopResults` R package.",
    caption = NULL,
    groupColumn = "cohort_name",
    groupAsColumn = FALSE,
    groupOrder = c("cohort2", "cohort1"),
    merge = "variable_name"
  )

In the examples above, we used the default style defined in the visOmopResults package (use tableStyle() to see these styles). However, it's possible to customise the appearance of different parts of the table to better suit your needs.

customising Table Styles

Let's start by applying a custom style to a <gt> table:

result |>
  formatTable(
    type = "gt",
    delim = "\n",
    style = list(
      "header" = list(gt::cell_text(weight = "bold"), 
                      gt::cell_fill(color = "orange")),
      "header_level" = list(gt::cell_text(weight = "bold"), 
                      gt::cell_fill(color = "yellow")),
      "column_name" = gt::cell_text(weight = "bold"),
      "group_label" = list(gt::cell_fill(color = "blue"),
                           gt::cell_text(color = "white", weight = "bold")),
      "title" = list(gt::cell_text(size = 20, weight = "bold")),
      "subtitle" = list(gt::cell_text(size = 15)),
      "body" = gt::cell_text(color = "red")
    ),
    na = "-",
    title = "My formatted table!",
    subtitle = "Created with the `visOmopResults` R package.",
    caption = NULL,
    groupColumn = "cohort_name",
    groupAsColumn = FALSE,
    groupOrder = c("cohort2", "cohort1"),
    merge = "variable_name"
  )

For creating a similarly styled <flextable>, the office R package is required to access specific formatting functions.

result |>
  formatTable(
    type = "flextable",
    delim = "\n",
    style = list(
      "header" = list(
        "cell" = officer::fp_cell(background.color = "orange"),
        "text" = officer::fp_text(bold = TRUE)),
      "header_level" = list(
        "cell" = officer::fp_cell(background.color = "yellow"),
        "text" = officer::fp_text(bold = TRUE)),
      "column_name" = list("text" = officer::fp_text(bold = TRUE)),
      "group_label" = list(
        "cell" = officer::fp_cell(background.color = "blue"),
        "text" = officer::fp_text(bold = TRUE, color = "white")),
      "title" = list("text" = officer::fp_text(bold = TRUE, font.size = 20)),
      "subtitle" = list("text" = officer::fp_text(font.size = 15)),
      "body" = list("text" = officer::fp_text(color = "red"))
    ),
    na = "-",
    title = "My formatted table!",
    subtitle = "Created with the `visOmopResults` R package.",
    caption = NULL,
    groupColumn = "cohort_name",
    groupAsColumn = FALSE,
    groupOrder = c("cohort2", "cohort1"),
    merge = "variable_name"
  )

visOmopResults documentation built on June 8, 2025, 12:44 p.m.