glue()

Updated May 19, 2026· Tidyverse

rgluetidyversestring-manipulation

Installation

Install the glue package from CRAN:

install.packages("glue")

The package is part of the tidyverse ecosystem and requires R 3.6.0 or later.

Basic Usage

The glue() function formats and interpolates strings, evaluating R expressions inside braces {...}. Unnamed arguments are strings to format; named arguments become temporary variables available within the braces.

name <- "Fred"
age <- 50

glue("My name is {name} and I am {age} years old.")
# My name is Fred and I am 50 years old.

Multiple arguments are concatenated using the .sep parameter, which defaults to an empty string:

glue("My name is ", name, " and I am ", age, " years old.")
# My name is Fred and I am 50 years old.

Named arguments create temporary variables scoped to the glue call:

glue("Hello {person}!", person = "Alice")
# Hello Alice!

Expressions inside braces are evaluated as R code:

x <- 10
y <- 3
glue("{x} + {y} = {x + y}")
# 10 + 3 = 13

Handling NA and NULL

By default, NA values are replaced with the string "NA":

x <- NA
glue("Value is {x}")
# Value is NA

To propagate NA values (keep them as R’s logical NA), set .na = NULL:

x <- NA
glue("Value is {x}", .na = NULL)
# NA  (logical NA, not the string "NA")

Similarly, NULL values are replaced with an empty string by default:

x <- NULL
glue("Value is {x}")
# Value is

To propagate NULL values as NA, use .null = NULL:

x <- NULL
glue("Value is {x}", .null = NULL)
# NA

Escaping and Custom Delimiters

To include literal braces in output, double them:

name <- "Fred"
glue("My name is {name}, not {{name}}.")
# My name is Fred, not {name}.

For formats that use braces heavily (such as LaTeX), provide alternative delimiters with .open and .close:

x <- 42
glue("Value is <<x>>.", .open = "<<", .close = ">>")
# Value is 42.

Text after # on a line is treated as a comment and ignored. Control the comment character via the .comment parameter:

glue("Hello # this is ignored")
# Hello 
glue("Hello # this is now literal", .comment = NULL)
# Hello # this is now literal

Use .literal = TRUE to treat quotes, backticks, and comments as literal characters.

Trimming Whitespace

By default, leading and trailing whitespace is trimmed from each string piece. Use .trim = FALSE to preserve whitespace:

glue("  Hello {name}  ", .trim = FALSE)
#   Hello Fred

Environment and Data Context

By default, expressions are evaluated in the calling environment. The .envir parameter accepts an environment, list, or data frame to lookup values from:

glue("{x} + {y} = {x + y}", .envir = list(x = 2, y = 3))
# 2 + 3 = 5

For lists and data frames in pipelines, use glue_data() which accepts list-like objects:

glue_data(list(x = 2, y = 3), "{x} + {y} = {x + y}")
# 2 + 3 = 5

In dplyr pipelines, glue_data() works with the pipe:

library(dplyr)
library(glue)

head(mtcars) %>%
  mutate(description = glue_data(., "{rownames(.)} has {hp} hp")) %>%
  pull(description)
# [1] "Mazda RX4 has 110 hp"     "Mazda RX4 Wag has 110 hp"
# [3] "Datsun 710 has 93 hp"     "Hornet 4 Drive has 110 hp"
# [5] "Hornet Sportabout has 175 hp" "Valiant has 105 hp"

glue_data(.x, ...): Like glue() but takes a list, data frame, or environment as the first argument, with values looked up before falling back to .envir.
glue_collapse(x, sep = ", ", last = " and "): Collapses a character vector into a single string with proper Oxford comma handling. Returns an empty glue object for zero-length input.
glue_safe() / glue_data_safe(): Safer variants that do not execute arbitrary code—only look up values via get(). Useful in Shiny apps where user input cannot be trusted.
glue_sql() / glue_data_sql() / glue_sql_collapse(): For safely building SQL queries, with automatic quoting of character values and identifiers. Character results are automatically quoted, and identifiers (surrounded by backticks) are handled appropriately.
glue_col() / glue_data_col(): Like glue() and glue_data() but support ANSI terminal styling via the crayon package.