GT.fmt_percent

GT.fmt_percent(
    self,
    columns=None,
    rows=None,
    decimals=2,
    drop_trailing_zeros=False,
    drop_trailing_dec_mark=True,
    scale_values=True,
    use_seps=True,
    pattern='{x}',
    sep_mark=',',
    dec_mark='.',
    force_sign=False,
    placement='right',
    incl_space=False,
    locale=None,
)

Format values as a percentage.

With numeric values in a gt table, we can perform percentage-based formatting. It is assumed the input numeric values are proportional values and, in this case, the values will be automatically multiplied by 100 before decorating with a percent sign (the other case is accommodated though setting scale_values to False). For more control over percentage formatting, we can use the following options:

Parameters

columns : SelectExpr = None

The columns to target. Can either be a single column name or a series of column names provided in a list.

rows : int | list[int] | None = None

In conjunction with columns=, we can specify which of their rows should undergo formatting. The default is all rows, resulting in all rows in targeted columns being formatted. Alternatively, we can supply a list of row indices.

decimals : int = 2

The decimals values corresponds to the exact number of decimal places to use. A value such as 2.34 can, for example, be formatted with 0 decimal places and it would result in "2". With 4 decimal places, the formatted value becomes "2.3400". The trailing zeros can be removed with drop_trailing_zeros=True.

drop_trailing_zeros : bool = False

A boolean value that allows for removal of trailing zeros (those redundant zeros after the decimal mark).

drop_trailing_dec_mark : bool = True

A boolean value that determines whether decimal marks should always appear even if there are no decimal digits to display after formatting (e.g., 23 becomes 23. if False). By default trailing decimal marks are not shown.

scale_values : bool = True

Should the values be scaled through multiplication by 100? By default this scaling is performed since the expectation is that incoming values are usually proportional. Setting to False signifies that the values are already scaled and require only the percent sign when formatted.

use_seps : bool = True

The use_seps option allows for the use of digit group separators. The type of digit group separator is set by sep_mark and overridden if a locale ID is provided to locale. This setting is True by default.

pattern : str = '{x}'

A formatting pattern that allows for decoration of the formatted value. The formatted value is represented by the {x} (which can be used multiple times, if needed) and all other characters will be interpreted as string literals.

sep_mark : str = ','

The string to use as a separator between groups of digits. For example, using sep_mark="," with a value of 1000 would result in a formatted value of "1,000". This argument is ignored if a locale is supplied (i.e., is not None).

dec_mark : str = '.'

The string to be used as the decimal mark. For example, using dec_mark="," with the value 0.152 would result in a formatted value of "0,152"). This argument is ignored if a locale is supplied (i.e., is not None).

force_sign : bool = False

Should the positive sign be shown for positive values (effectively showing a sign for all values except zero)? If so, use True for this option. The default is False, where only negative numbers will display a minus sign.

placement : str = 'right'

This option governs the placement of the percent sign. This can be either be "right" (the default) or "left".

incl_space : bool = False

An option for whether to include a space between the value and the percent sign. The default is to not introduce a space character.

locale : str | None = None

An optional locale identifier that can be used for formatting values according the locale’s rules. Examples include "en" for English (United States) and "fr" for French (France).

Returns

: GT

The GT object is returned. This is the same object that the method is called on so that we can facilitate method chaining.

Adapting output to a specific locale

This formatting method 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 methods that have a locale argument).

Examples

Let’s use the towny dataset as the input table. With the fmt_percent() method, we’ll format the pop_change_2016_2021_pct column to to display values as percentages (to two decimal places).

from great_tables import GT
from great_tables.data import towny

towny_mini = (
    towny[["name", "pop_change_2016_2021_pct"]]
    .head(10)
)

(GT(towny_mini).fmt_percent("pop_change_2016_2021_pct", decimals=2))
name pop_change_2016_2021_pct
Addington Highlands 9.32%
Adelaide Metcalfe 0.70%
Adjala-Tosorontio 0.13%
Admaston/Bromley 2.04%
Ajax 5.84%
Alberton −1.55%
Alfred and Plantagenet 2.78%
Algonquin Highlands 10.08%
Alnwick/Haldimand 8.79%
Amaranth 6.08%

See Also

The functional version of this method, val_fmt_percent(), allows you to format a single numerical value (or a list of them).