Merge columns to a value-with-uncertainty column

The cols_merge_uncert() function is a specialized variant of the cols_merge() function. It takes as input a base value column (col_val) and either: (1) a single uncertainty column, or (2) two columns representing lower and upper uncertainty bounds. These columns will be essentially merged in a single column (that of col_val). What results is a column with values and associated uncertainties (e.g., 12.0 ± 0.1), and any columns specified in col_uncert are hidden from appearing the output table.

Usage

cols_merge_uncert(
  data,
  col_val,
  col_uncert,
  rows = everything(),
  sep = " +/- ",
  autohide = TRUE
)

Arguments

data

The gt table data object

obj:<gt_tbl> // required

This is the gt table object that is commonly created through use of the gt() function.

col_val

Column to target for base values

<column-targeting expression> // required

The column that contains values for the start of the range. While select helper functions such as starts_with() and ends_with() can be used for column targeting, it's recommended that a single column name be used. This is to ensure that exactly one column is provided here.

col_uncert

Column or columns to target for uncertainty values

<column-targeting expression> // required

The most common case involves supplying a single column with uncertainties; these values will be combined with those in col_val. Less commonly, the lower and upper uncertainty bounds may be different. For that case, two columns representing the lower and upper uncertainty values away from col_val, respectively, should be provided. While select helper functions such as starts_with() and ends_with() can be used for column targeting, it's recommended that one or two column names be explicitly provided in a vector.

rows

Rows to target

<row-targeting expression> // default: everything()

In conjunction with columns, we can specify which of their rows should participate in the merging process. The default everything() results in all rows in columns being formatted. Alternatively, we can supply a vector of row IDs within c(), a vector of row indices, or a select helper function. Examples of select helper functions include starts_with(), ends_with(), contains(), matches(), one_of(), num_range(), and everything(). We can also use expressions to filter down to the rows we need (e.g., [colname_1] > 100 & [colname_2] < 50).

sep

Separator text for uncertainties

scalar<character> // default: " +/- "

The separator text that contains the uncertainty mark for a single uncertainty value. The default value of " +/- " indicates that an appropriate plus/minus mark will be used depending on the output context. Should you want this special symbol to be taken literally, it can be supplied within the I() function.

autohide

Automatic hiding of the col_uncert column(s)

scalar<logical> // default: TRUE

An option to automatically hide any columns specified in col_uncert. Any columns with their state changed to 'hidden' will behave the same as before, they just won't be displayed in the finalized table.

Value

An object of class gt_tbl.

Comparison with other column-merging functions

This function could be somewhat replicated using cols_merge() in the case where a single column is supplied for col_uncert, however, cols_merge_uncert() employs the following specialized semantics for NA handling:

NAs in col_val result in missing values for the merged column (e.g., NA + 0.1 = NA)
NAs in col_uncert (but not col_val) result in base values only for the merged column (e.g., 12.0 + NA = 12.0)
NAs both col_val and col_uncert result in missing values for the merged column (e.g., NA + NA = NA)

Any resulting NA values in the col_val column following the merge operation can be easily formatted using the sub_missing() function.

This function is part of a set of four column-merging functions. The other three are the general cols_merge() function and the specialized cols_merge_range() and cols_merge_n_pct() functions. These functions operate similarly, where the non-target columns can be optionally hidden from the output table through the hide_columns or autohide options.

Examples

Let's use the exibble dataset to create a simple, two-column gt table (keeping only the num and currency columns). We'll format the num column with the fmt_number() function. Next we merge the currency and num columns into the currency column; this will contain a base value and an uncertainty and it's all done using the cols_merge_uncert() function. After the merging process, the column label for the currency column is updated with cols_label() to better describe the content.

exibble |>
  dplyr::select(num, currency) |>
  dplyr::slice(1:7) |>
  gt() |>
  fmt_number(
    columns = num,
    decimals = 3,
    use_seps = FALSE
  ) |>
  cols_merge_uncert(
    col_val = currency,
    col_uncert = num
  ) |>
  cols_label(currency = "value + uncert.")

This image of a table was generated from the first code example in the `cols_merge_uncert()` help file.

Function ID

5-15

Function Introduced

v0.2.0.5 (March 31, 2020)