glue (version 1.8.0)

glue: Format and interpolate a string

Description

Expressions enclosed by braces will be evaluated as R code. Long strings are broken by line and concatenated together. Leading whitespace and blank lines from the first and last lines are automatically trimmed.

Usage

glue_data(
  .x,
  ...,
  .sep = "",
  .envir = parent.frame(),
  .open = "{",
  .close = "}",
  .na = "NA",
  .null = character(),
  .comment = "#",
  .literal = FALSE,
  .transformer = identity_transformer,
  .trim = TRUE
)
glue(
  ...,
  .sep = "",
  .envir = parent.frame(),
  .open = "{",
  .close = "}",
  .na = "NA",
  .null = character(),
  .comment = "#",
  .literal = FALSE,
  .transformer = identity_transformer,
  .trim = TRUE
)

Value

A glue object, as created by as_glue().

Arguments

.x

[listish]
An environment, list, or data frame used to lookup values.

...

[expressions]
Unnamed arguments are taken to be expression string(s) to format. Multiple inputs are concatenated together before formatting. Named arguments are taken to be temporary variables available for substitution.

For glue_data(), elements in ... override the values in .x.

.sep

[character(1): ‘""’]
Separator used to separate elements.

.envir

[environment: parent.frame()]
Environment to evaluate each expression in. Expressions are evaluated from left to right. If .x is an environment, the expressions are evaluated in that environment and .envir is ignored. If NULL is passed, it is equivalent to emptyenv().

.open

[character(1): ‘\{’]
The opening delimiter. Doubling the full delimiter escapes it.

.close

[character(1): ‘\}’]
The closing delimiter. Doubling the full delimiter escapes it.

.na

[character(1): ‘NA’]
Value to replace NA values with. If NULL missing values are propagated, that is an NA result will cause NA output. Otherwise the value is replaced by the value of .na.

.null

[character(1): ‘character()’]
Value to replace NULL values with. If character() whole output is character(). If NULL all NULL values are dropped (as in paste0()). Otherwise the value is replaced by the value of .null.

.comment

[character(1): ‘#’]
Value to use as the comment character.

.literal

[boolean(1): ‘FALSE’]
Whether to treat single or double quotes, backticks, and comments as regular characters (vs. as syntactic elements), when parsing the expression string. Setting .literal = TRUE probably only makes sense in combination with a custom .transformer, as is the case with glue_col(). Regard this argument (especially, its name) as experimental.

.transformer

[function]
A function taking two arguments, text and envir, where text is the unparsed string inside the glue block and envir is the execution environment. A .transformer lets you modify a glue block before, during, or after evaluation, allowing you to create your own custom glue()-like functions. See vignette("transformers") for examples.

.trim

[logical(1): ‘TRUE’]
Whether to trim the input template with trim() or not.

See Also

https://www.python.org/dev/peps/pep-0498/ and https://www.python.org/dev/peps/pep-0257/ upon which this is based.

Examples

name <- "Fred"
age <- 50
anniversary <- as.Date("1991-10-12")
glue('My name is {name},',
  'my age next year is {age + 1},',
  'my anniversary is {format(anniversary, "%A, %B %d, %Y")}.')

# single braces can be inserted by doubling them
glue("My name is {name}, not {{name}}.")

# Named arguments can be used to assign temporary variables.
glue('My name is {name},',
  ' my age next year is {age + 1},',
  ' my anniversary is {format(anniversary, "%A, %B %d, %Y")}.',
  name = "Joe",
  age = 40,
  anniversary = as.Date("2001-10-12"))

# `glue()` can also be used in user defined functions
intro <- function(name, profession, country){
  glue("My name is {name}, a {profession}, from {country}")
}
intro("Shelmith", "Senior Data Analyst", "Kenya")
intro("Cate", "Data Scientist", "Kenya")

# `glue_data()` is useful in magrittr pipes
if (require(magrittr)) {

mtcars %>% glue_data("{rownames(.)} has {hp} hp")

# Or within dplyr pipelines
if (require(dplyr)) {

head(iris) %>%
  mutate(description = glue("This {Species} has a petal length of {Petal.Length}"))

}}

# Alternative delimiters can also be used if needed
one <- "1"
glue("The value of $e^{2\\pi i}$ is $<>$.", .open = "<<", .close = ">>")