stri_sprintf: Format Strings

Description

stri_sprintf (synonym: stri_string_format) is a Unicode-aware replacement for and enhancement of the built-in sprintf function. Moreover, stri_printf prints formatted strings.

Usage

stri_sprintf(
  format,
  ...,
  na_string = NA_character_,
  inf_string = "Inf",
  nan_string = "NaN",
  use_length = FALSE
)

stri_string_format(
  format,
  ...,
  na_string = NA_character_,
  inf_string = "Inf",
  nan_string = "NaN",
  use_length = FALSE
)

stri_printf(
  format,
  ...,
  file = "",
  sep = "\n",
  append = FALSE,
  na_string = "NA",
  inf_string = "Inf",
  nan_string = "NaN",
  use_length = FALSE
)

Arguments

format

character vector of format strings

...

vectors (coercible to integer, real, or character)

na_string

single string to represent missing values; if NA, missing values in ... result in the corresponding outputs be missing too; use "NA" for compatibility with base R

inf_string

single string to represent the (unsigned) infinity (NA allowed)

nan_string

single string to represent the not-a-number (NA allowed)

use_length

single logical value; should the number of code points be used when applying modifiers such as %20s instead of the total code point width?

file

see cat

sep

see cat

append

see cat

Details

Vectorized over format and all vectors passed via ....

Unicode code points may have various widths when printed on the console (compare stri_width). These functions, by default (see the use_length argument), take this into account.

These functions are not locale sensitive. For instance, numbers are always formatted in the “POSIX” style, e.g., -123456.789 (no thousands separator, dot as a fractional separator). Such a feature might be added at a later date, though.

All arguments passed via ... are evaluated. If some of them are unused, a warning is generated. Too few arguments result in an error.

Note that stri_printf treats missing values in ... as "NA" strings by default.

All format specifiers supported sprintf are also available here. For the formatting of integers and floating-point values, currently the system std::snprintf() is called, but this may change in the future. Format specifiers are normalized and necessary sanity checks are performed.

Supported conversion specifiers: dioxX (integers) feEgGaA (floats) and s (character strings). Supported flags: - (left-align), + (force output sign or blank when NaN or NA; numeric only), <space> (output minus or space for a sign; numeric only) 0 (pad with 0s; numeric only), # (alternative output of some numerics).

Value

stri_printf is used for its side effect, which is printing text on the standard output or other connection/file. Hence, it returns invisible(NULL).

The other functions return a character vector.

Author(s)

Marek Gagolewski and other contributors

References

printf in glibc, https://man.archlinux.org/man/printf.3

printf format strings – Wikipedia, https://en.wikipedia.org/wiki/Printf_format_string

See Also

The official online manual of stringi at https://stringi.gagolewski.com/

Other length: %s$%(), stri_isempty(), stri_length(), stri_numbytes(), stri_pad_both(), stri_width()

Examples

stri_printf("%4s=%.3f", c("e", "e\u00b2", "\u03c0", "\u03c0\u00b2"),
    c(exp(1), exp(2), pi, pi^2))
##    e=2.718
##   e²=7.389
##    π=3.142
##   π²=9.870
x <- c(
  "xxabcd",
  "xx\u0105\u0106\u0107\u0108",
  stri_paste(
    "\u200b\u200b\u200b\u200b",
    "\U0001F3F4\U000E0067\U000E0062\U000E0073\U000E0063\U000E0074\U000E007F",
    "abcd"
  ))
stri_printf("[%10s]", x)  # minimum width = 10
## [    xxabcd]
## [    xxąĆćĈ]
## [    ​​​​🏴󠁧󠁢󠁳󠁣󠁴󠁿abcd]
stri_printf("[%-10.3s]", x)  # output of max width = 3, but pad to width of 10
## [xxa       ]
## [xxą       ]
## [​​​​🏴󠁧󠁢󠁳󠁣󠁴󠁿a       ]
stri_printf("[%10s]", x, use_length=TRUE)  # minimum number of Unicode code points = 10
## [    xxabcd]
## [    xxąĆćĈ]
## [​​​​🏴󠁧󠁢󠁳󠁣󠁴󠁿abcd]
# vectorization wrt all arguments:
p <- runif(10)
stri_sprintf(ifelse(p > 0.5, "P(Y=1)=%1$.2f", "P(Y=0)=%2$.2f"), p, 1-p)
##  [1] "P(Y=0)=0.71" "P(Y=1)=0.79" "P(Y=0)=0.59" "P(Y=1)=0.88" "P(Y=1)=0.94"
##  [6] "P(Y=0)=0.95" "P(Y=1)=0.53" "P(Y=1)=0.89" "P(Y=1)=0.55" "P(Y=0)=0.54"
# using a "preformatted" logical vector:
x <- c(TRUE, FALSE, FALSE, NA, TRUE, FALSE)
stri_sprintf("%s) %s", letters[seq_along(x)], c("\u2718", "\u2713")[x+1])
## [1] "a) ✓" "b) ✘" "c) ✘" NA     "e) ✓" "f) ✘"
# custom NA/Inf/NaN strings:
stri_printf("%+10.3f", c(-Inf, -0, 0, Inf, NaN, NA_real_),
    na_string="<NA>", nan_string="\U0001F4A9", inf_string="\u221E")
##         -∞
##     -0.000
##     +0.000
##         +∞
##         💩
##       <NA>
stri_sprintf("UNIX time %1$f is %1$s.", Sys.time())
## [1] "UNIX time 1630629214.282479 is 2021-09-03 10:33:34."
# the following do not work in sprintf()
stri_sprintf("%1$#- *2$.*3$f", 1.23456, 10, 3)  # two asterisks
## [1] " 1.235    "
stri_sprintf(c("%s", "%f"), pi)  # re-coercion needed
## [1] "3.14159265358979" "3.141593"
stri_sprintf("%1$s is %1$f UNIX time.", Sys.time())  # re-coercion needed
## [1] "2021-09-03 10:33:34 is 1630629214.284802 UNIX time."
stri_sprintf(c("%d", "%s"), factor(11:12))  # re-coercion needed
## [1] "1"  "12"
stri_sprintf(c("%s", "%d"), factor(11:12))  # re-coercion needed
## [1] "11" "2"