With numeric values in a 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
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.
n_sigfig:int | None=None
A option to format numbers to n significant figures. By default, this is None and thus number values will be formatted according to the number of decimal places set via decimals. If opting to format according to the rules of significant figures, n_sigfig must be a number greater than or equal to 1. Any values passed to the decimals and drop_trailing_zeros arguments will be ignored.
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_by:float=1
All numeric values will be multiplied by the scale_by value before undergoing formatting. Since the default value is 1, no values will be changed unless a different multiplier value is supplied.
exp_style:str='x10n'
Style of formatting to use for the scientific notation formatting. By default this is "x10n" but other options include using a single letter (e.g., "e", "E", etc.), a letter followed by a "1" to signal a minimum digit width of one, or "low-ten" for using a stylized "10" marker.
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.
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_m:bool=False
Should the plus sign be shown for positive values of the mantissa (first component)? This would effectively show a sign for all values except zero on the first numeric component of the notation. If so, use True (the default for this is False), where only negative numbers will display a sign.
force_sign_n:bool=False
Should the plus sign be shown for positive values of the exponent (second component)? This would effectively show a sign for all values except zero on the second numeric component of the notation. If so, use True (the default for this is False), where only negative numbers will display a sign.
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).
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 a value be provided in dec_mark it 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
For this example, we’ll use the exibble dataset as the input table. With the fmt_scientific() method, we’ll format the num column to contain values in scientific formatting.
from great_tables import GT, exibble( GT(exibble) .fmt_scientific(columns="num"))
num
char
fctr
date
time
datetime
currency
row
group
1.11 × 10−1
apricot
one
2015-01-15
13:35
2018-01-01 02:22
49.95
row_1
grp_a
2.22
banana
two
2015-02-15
14:40
2018-02-02 14:33
17.95
row_2
grp_a
3.33 × 101
coconut
three
2015-03-15
15:45
2018-03-03 03:44
1.39
row_3
grp_a
4.44 × 102
durian
four
2015-04-15
16:50
2018-04-04 15:55
65100.0
row_4
grp_a
5.55 × 103
five
2015-05-15
17:55
2018-05-05 04:00
1325.81
row_5
grp_b
fig
six
2015-06-15
2018-06-06 16:11
13.255
row_6
grp_b
7.77 × 105
grapefruit
seven
19:10
2018-07-07 05:22
row_7
grp_b
8.88 × 106
honeydew
eight
2015-08-15
20:20
0.44
row_8
grp_b
See Also
The functional version of this method, val_fmt_scientific(), allows you to format a single numerical value (or a list of them).