kutils (version 1.73)

truncsmart: Cuts a string at a specified linewidth, trying to align cut with a separator

Description

Some strings are simply too long. We don't want to chop them exactly at, say, 40 characters, if we could allow 42 and chop on a space or other separator. We'd rather chop at 37 if there is a separator, rather than terminate a word exactly at 40. This function shortens them and attempt to cut at a separator, allowing for a user specified fudge-factor (the tol parameter).

Usage

truncsmart(
  x,
  target = 20,
  tol = c(5, 3),
  separators = c(" ", "_", ";", ","),
  capwidth = 1
)

Value

shorter string truncated at acceptable separators when found

Arguments

x

character or vector of characters

target

Goal for result length, in characters

tol

number of characters forward/back to check; if single value then only backwards checking

separators

characters at which truncation is preferred, such as space or underscore.

capwidth

penalty for capital characters

Author

Paul Johnson <[e-mail]>

Details

The default capwidth value is 1, so the calculations treat all letters equally. In practice, we notice trouble when some strings are written in ALL CAPS and they are longer than the same information in lower case letters. We have decided to allow a user-specified penalty for capital letters. If each capital counts for, say 1.2 ordinary letters, then we may end up truncating the string on an earlier separator.

There's some approximation here. The capital-penalized widths are calculated for all characters and then we left-shift the target value so that it is equal to the last penalized value that is under the target length. Then the "look to the left" and "look to the right" logic begins. That looking logic ignores the capital letter penalty, it is treating all letters the same.

Examples

x <- "Aasdf asdIasdf fW_asd asd aasjdf_as fasdasdfasdfasd"
truncsmart(x, target = 10, tol = c(5, 2))
truncsmart(x, target = 10, tol = c(1, 4))
truncsmart(x, target = 10, tol = c(5, 2), capwidth = 1.2)
truncsmart(x, target = 20, tol = c(5, 2))
truncsmart(x, target = 20, tol = c(10,10), capwidth = 2)
truncsmart(x, target = 20, tol = c(10,10), capwidth = 3)
truncsmart(x, target = 20, tol = c(10,10), capwidth = 4)
truncsmart(x, target = 20, tol = c(10,10), capwidth = 6)