| fmt_scientific {gt} | R Documentation |
Format values to scientific notation
Description
With numeric values in a gt table, we can perform formatting so that the
targeted values are rendered in scientific notation, where extremely large or
very small numbers can be expressed in a more practical fashion. Here,
numbers are written in the form of a mantissa (m) and an exponent (n)
with the construction m x 10^n or mEn. The mantissa component is a
number between 1 and 10. For instance, 2.5 x 10^9 can be used to
represent the value 2,500,000,000 in scientific notation. In a similar way,
0.00000012 can be expressed as 1.2 x 10^-7. Due to its ability to describe
numbers more succinctly and its ease of calculation, scientific notation is
widely employed in scientific and technical domains.
We have fine control over the formatting task, with the following options:
decimals: choice of the number of decimal places, option to drop trailing zeros, and a choice of the decimal symbol
scaling: we can choose to scale targeted values by a multiplier value
pattern: option to use a text pattern for decoration of the formatted values
locale-based formatting: providing a locale ID will result in formatting specific to the chosen locale
Usage
fmt_scientific(
data,
columns = everything(),
rows = everything(),
decimals = 2,
n_sigfig = NULL,
drop_trailing_zeros = FALSE,
drop_trailing_dec_mark = TRUE,
scale_by = 1,
exp_style = "x10n",
pattern = "{x}",
sep_mark = ",",
dec_mark = ".",
force_sign_m = FALSE,
force_sign_n = FALSE,
locale = NULL
)
Arguments
data |
The gt table data object
This is the gt table object that is commonly created through use of the
|
columns |
Columns to target
Can either be a series of column names provided in |
rows |
Rows to target
In conjunction with |
decimals |
Number of decimal places
This corresponds to the exact number of decimal places to use. A value
such as |
n_sigfig |
Number of significant figures
A option to format numbers to n significant figures. By default, this is
|
drop_trailing_zeros |
Drop any trailing zeros
A logical value that allows for removal of trailing zeros (those redundant zeros after the decimal mark). |
drop_trailing_dec_mark |
Drop the trailing decimal mark
A logical value that determines whether decimal marks should always appear
even if there are no decimal digits to display after formatting (e.g., |
scale_by |
Scale values by a fixed multiplier
All numeric values will be multiplied by the |
exp_style |
Style declaration for exponent formatting
Style of formatting to use for the scientific notation formatting. By
default this is |
pattern |
Specification of the formatting pattern
A formatting pattern that allows for decoration of the formatted value. The
formatted value is represented by the |
sep_mark |
Separator mark for digit grouping
The string to use as a separator between groups of digits. For example,
using |
dec_mark |
Decimal mark
The string to be used as the decimal mark. For example, using
|
force_sign_m, force_sign_n |
Forcing the display of a positive sign
Should the plus sign be shown for positive values of the mantissa (first
component, |
locale |
Locale identifier
An optional locale identifier that can be used for formatting values
according the locale's rules. Examples include |
Value
An object of class gt_tbl.
Compatibility of formatting function with data values
fmt_scientific() is compatible with body cells that are of the "numeric"
or "integer" types. Any other types of body cells are ignored during
formatting. This is to say that cells of incompatible data types may be
targeted, but there will be no attempt to format them.
Targeting cells with columns and rows
Targeting of values is done through columns and additionally by rows (if
nothing is provided for rows then entire columns are selected). The
columns argument allows us to target a subset of cells contained in the
resolved columns. We say resolved because aside from declaring column names
in c() (with bare column names or names in quotes) we can use
tidyselect-style expressions. This can be as basic as supplying a select
helper like starts_with(), or, providing a more complex incantation like
where(~ is.numeric(.x) && max(.x, na.rm = TRUE) > 1E6)
which targets numeric columns that have a maximum value greater than
1,000,000 (excluding any NAs from consideration).
By default all columns and rows are selected (with the everything()
defaults). Cell values that are incompatible with a given formatting function
will be skipped over, like character values and numeric fmt_*()
functions. So it's safe to select all columns with a particular formatting
function (only those values that can be formatted will be formatted), but,
you may not want that. One strategy is to format the bulk of cell values with
one formatting function and then constrain the columns for later passes with
other types of formatting (the last formatting done to a cell is what you get
in the final output).
Once the columns are targeted, we may also target the rows within those
columns. This can be done in a variety of ways. If a stub is present, then we
potentially have row identifiers. Those can be used much like column names in
the columns-targeting scenario. We can use simpler tidyselect-style
expressions (the select helpers should work well here) and we can use quoted
row identifiers in c(). It's also possible to use row indices (e.g.,
c(3, 5, 6)) though these index values must correspond to the row numbers of
the input data (the indices won't necessarily match those of rearranged rows
if row groups are present). One more type of expression is possible, an
expression that takes column values (can involve any of the available columns
in the table) and returns a logical vector. This is nice if you want to base
formatting on values in the column or another column, or, you'd like to use a
more complex predicate expression.
Compatibility of arguments with the from_column() helper function
from_column() can be used with certain arguments of fmt_scientific() to
obtain varying parameter values from a specified column within the table.
This means that each row could be formatted a little bit differently. These
arguments provide support for from_column():
-
decimals -
drop_trailing_zeros -
drop_trailing_dec_mark -
scale_by -
exp_style -
pattern -
sep_mark -
dec_mark -
force_sign_m -
force_sign_n -
locale
Please note that for all of the aforementioned arguments, a from_column()
call needs to reference a column that has data of the correct type (this is
different for each argument). Additional columns for parameter values can be
generated with cols_add() (if not already present). Columns that contain
parameter data can also be hidden from final display with cols_hide().
Finally, there is no limitation to how many arguments the from_column()
helper is applied so long as the arguments belong to this closed set.
Adapting output to a specific locale
This formatting function can adapt outputs according to a provided locale
value. Examples include "en" for English (United States) and "fr" for
French (France). The use of a valid locale ID here means separator and
decimal marks will be correct for the given locale. Should any values be
provided in sep_mark or dec_mark, they will be overridden by the locale's
preferred values.
Note that a locale value provided here will override any global locale
setting performed in gt()'s own locale argument (it is settable there as
a value received by all other functions that have a locale argument). As a
useful reference on which locales are supported, we can call info_locales()
to view an info table.
Examples
Let's define a data frame that contains two columns of values (one small
and one large). After creating a simple gt table from small_large_tbl
we'll call fmt_scientific() on both columns.
small_large_tbl <-
dplyr::tibble(
small = 10^(-12:-1),
large = 10^(1:12)
)
small_large_tbl |>
gt() |>
fmt_scientific()
The default method of styling the notation uses the 'm x 10^n'
construction but this can be changed to a 'mEn' style via the exp_style
argument. We can supply any single letter here and optionally affix a "1"
to indicate there should not be any zero-padding of the n value. Two calls
of fmt_scientific() are used here to show different options for styling
in scientific notation.
small_large_tbl |>
gt() |>
fmt_scientific(
columns = small,
exp_style = "E"
) |>
fmt_scientific(
columns = large,
exp_style = "e1",
force_sign_n = TRUE
)
Taking a portion of the reactions dataset, we can create a gt table
that contains reaction rate constants that should be expressed in scientific
notation. All of the numeric values in the filtered table require that
type of formatting so fmt_scientific() can be called without requiring any
specification of column names in the columns argument. By default, the
number of decimal places is fixed to 2, which is fine for this table.
reactions |>
dplyr::filter(cmpd_type == "mercaptan") |>
dplyr::select(cmpd_name, cmpd_formula, OH_k298, Cl_k298, NO3_k298) |>
gt(rowname_col = "cmpd_name") |>
tab_header(title = "Gas-phase reactions of selected mercaptan compounds") |>
tab_spanner(
label = md("Reaction Rate Constant (298 K),<br>{{cm^3 molecules^-1 s^-1}}"),
columns = ends_with("k298")
) |>
fmt_chem(columns = cmpd_formula) |>
fmt_scientific() |>
sub_missing() |>
cols_label(
cmpd_formula = "",
OH_k298 = "OH",
NO3_k298 = "{{%NO3%}}",
Cl_k298 = "Cl"
) |>
opt_stylize() |>
opt_horizontal_padding(scale = 3) |>
opt_table_font(font = google_font("IBM Plex Sans")) |>
tab_options(stub.font.weight = "500")
The constants table contains a plethora of data on the fundamental
physical constants and values range from very small to very large, warranting
the use of figures in scientific notation. Because the values differ in the
degree of measurement precision, the dataset has columns (sf_value and
sf_uncert) that include the number of significant figures for each
measurement value and for the associated uncertainty. We can use the
n_sigfig argument of fmt_scientific() in conjunction with the
from_column() helper to format each value and its uncertainty to the proper
number of significant digits.
constants |>
dplyr::filter(grepl("Planck", name)) |>
gt() |>
fmt_scientific(
columns = value,
n_sigfig = from_column(column = "sf_value")
) |>
fmt_scientific(
columns = uncert,
n_sigfig = from_column(column = "sf_uncert")
) |>
cols_hide(columns = starts_with("sf")) |>
fmt_units(columns = units) |>
sub_missing(missing_text = "")
Function ID
3-3
Function Introduced
v0.2.0.5 (March 31, 2020)
See Also
The vector-formatting version of this function:
vec_fmt_scientific().
Other data formatting functions:
data_color(),
fmt(),
fmt_auto(),
fmt_bins(),
fmt_bytes(),
fmt_chem(),
fmt_country(),
fmt_currency(),
fmt_date(),
fmt_datetime(),
fmt_duration(),
fmt_email(),
fmt_engineering(),
fmt_flag(),
fmt_fraction(),
fmt_icon(),
fmt_image(),
fmt_index(),
fmt_integer(),
fmt_markdown(),
fmt_number(),
fmt_partsper(),
fmt_passthrough(),
fmt_percent(),
fmt_roman(),
fmt_spelled_num(),
fmt_tf(),
fmt_time(),
fmt_units(),
fmt_url(),
sub_large_vals(),
sub_missing(),
sub_small_vals(),
sub_values(),
sub_zero()