stringplus

Combine strings using builtin infix operators.

Install

remotes::install_github("traversc/stringplus")

Examples

Using the & operator concatenates two strings.

"hello" & "world"
# output: "helloworld"

Using the | operator formats a string using sprintf or glue::glue depending on whether the second argument is named.

# Using sprintf
"C:/folder/%s/file.txt" | "subfolder"

# Using glue::glue
"C:/folder/{var}/file.txt" | c(var="subfolder")

# Output: "C:/folder/subfolder/file.txt"

Using a different infix operator

You can change the infix operators in the above examples by calling set_string_ops.

set_string_ops(concat = "+", format = "*", permanent = FALSE)
"hello" + "world"
# output: "helloworld"

"C:/folder/%s/file.txt" * "subfolder"
# Output: "C:/folder/subfolder/file.txt"

Setting permanent = TRUE will make these settings persist between sessions.

Details

Many infix operators in base R functions are hard coded to return an error on character vector inputs. This is unlike the behavior for custom classes, where they can be modified using the R dispatch system.

While these operators can't be modified for string input, they CAN be overwritten. In stringplus, the built-in operators are overwritten to check if the first argument is a character vector; if so it concatenates (or formats) the two arguments, if not it falls back to the built-in operator.

This overridden function should not interfere with normal dispatch.

set_string_ops(concat = "+", format = "*", permanent = FALSE)
library(ggplot2)

ggplot(mtcars, aes(x = mpg, y = cyl)) + geom_point()

1 + 2 # output: 3
1 * 2 # output: 2

setClass("Zoo", slots=list(animals="numeric"))
setMethod("+", signature = c("Zoo", "Zoo"),
          function(e1, e2) new("Zoo", animals=e1@animals + e2@animals))
sandiego <- new("Zoo", animals=4000)
columbus <- new("Zoo", animals=7000)
sandiego + columbus
# Output
# An object of class "Zoo"
# Slot "animals":
# [1] 11000

Notes

Isn't there a performance cost?

• Yes, there is a small performance cost around 1-2 microsecond per op

Wouldn't this interfere with class dispatch methods?

• No, see examples

Could this break something else?

• I don't think so, please let me know if you can think of a way it does!