library(sprintfr)
library(magrittr)
library(knitr)

Base Components

Let’s see what kind of componenets we can use in our string format.

string_base %>% kable

integer	octal	hex	double	scientific	auto	binary	string	percent
i	o	x	f	e	g	a	s	%

Each of these base time can be used in a string format:

string_format(double, " ", integer)

## [1] "%.f %.i"

Modifications

Each base component can be modified with flags or changing options. The default bases will always have no options or flags selected. Each option and flag has a corresponding function.

You can see options available.

string_option %>% kable

before_decimal	after_decimal	use_input
number of digits before the decimal place	number of digits after the decimal place	sprintf input argument number

Option assignment has two arguments, an object to modify and new value.

string_format(double %>% use_input(2))

## [1] "%2$.f"

You can also see flags available.

string_flag %>% kable

left_justify	always_sign	prefix_space	zero_pad	hex_prefix	always_decimal	remove_zeros
-	+		0	#	#	#

Flag assignment has two arguments, an object to modify and new value. By default, the second argument is TRUE. Flags can be turned off by assigning a value of FALSE. For more information about flags, see the sprintf documentation.

string_format(double %>% zero_pad)

## [1] "%0.f"

string_format(double %>% zero_pad %>% zero_pad(FALSE))

## [1] "%.f"

Example

Let’s build a complicated string format for fun.

string_format(list(double %>% 
                     zero_pad,
                   "1%",
                   double %>% 
                     left_justify) %>%
                use_input(1) %>%
                always_sign %>%
                before_decimal(3) %>%
                after_decimal(0),
              sep = " and ")

## [1] "%1$+03.0f and 1%% and %1$-+3.0f"

sprintfr is clever about applying modifications over lists. This allows bulk modification. Raw strings can be modified (as “text” above), but it will not effect how they are displayed. Percentages in raw strings will automatically be doubled. Note that the sep argument will be used if named, and defaults to “”. This works the same way as in base paste.