stringr::str_c()

str_c(..., sep = "", collapse = NULL)

Returns character· Updated May 12, 2026· Tidyverse

stringrstringcombinepastetidyverse

The str_c() function from stringr combines multiple strings into one. It is a consistent wrapper around paste0() with helpful defaults and additional features like handling missing values and the collapse argument for joining vector elements.

Syntax

str_c(..., sep = "", collapse = NULL)

Parameters

Parameter	Type	Default	Description
`...`	character	Required	Two or more character vectors to combine
`sep`	character	""	String to insert between each pair of combined elements
`collapse`	character	NULL	If not NULL, collapse a vector into a single string with this separator

Examples

Basic usage

library(stringr)

# Combine two strings
str_c("Hello", "World")
# [1] "HelloWorld"

# With separator
str_c("Hello", "World", sep = " ")
# [1] "Hello World"

Combining vectors

# Element-wise combination
str_c("a", 1:3)
# [1] "a1" "a2" "a3"

# Using with paste0-style behavior
str_c("x", "y", "z")
# [1] "xyz"

Collapse argument

# Join vector into single string
str_c(letters[1:5], collapse = ", ")
# [1] "a, b, c, d, e"

# Combine sep and collapse
str_c(c("a", "b", "c"), c("1", "2", "3"), sep = "-", collapse = "|")
# [1] "a-1|b-2|c-3"

Using in dplyr pipelines

library(dplyr)

df <- data.frame(
  first_name = c("John", "Jane", "Bob"),
  last_name = c("Doe", "Smith", "Johnson")
)

df %>%
  mutate(full_name = str_c(first_name, " ", last_name))
#   first_name  last_name     full_name
# 1       John       Doe   John Doe
# 2       Jane     Smith   Jane Smith
# 3       Bob   Johnson Bob Johnson

Creating file paths

# Build file paths safely
path_parts <- c("home", "user", "documents", "file.txt")
str_c(path_parts, collapse = "/")
# [1] "home/user/documents/file.txt"

# With base and filename
str_c("https://", "example.com", "/", "page", ".html")
# [1] "https://example.com/page.html"

Handling missing values

# NA propagates by default
str_c("a", NA, "b")
# [1] NA

# Use str_replace_na to convert NA to string
str_c(str_replace_na(c("a", NA, "b")), collapse = ", ")
# [1] "a, NA, b"

Differences from base R paste()

Feature	str_c()	paste()
Default sep	"" (empty)	” ” (space)
NA handling	Returns NA	Returns “NA” as string
Recycling	Tidyverse recycling rules	Base R recycling
Default	No deparse.labels	Includes deparse.labels

# str_c uses empty string by default
str_c("a", "b")
# [1] "ab"

# paste uses space by default
paste("a", "b")
# [1] "a b"

# Equivalent to str_c
paste0("a", "b")
# [1] "ab"

Common Patterns

Dynamic labels: Create labels for plots and tables
URL building: Construct URLs from components
File paths: Build file paths safely
Text generation: Generate dynamic text messages

Dynamic plot labels

# Create dynamic axis labels
x_var <- "mpg"
y_var <- "disp"

x_label <- str_c("Miles per Gallon (", x_var, ")")
y_label <- str_c("Displacement (", y_var, ")")

x_label
# [1] "Miles per Gallon (mpg)"

y_label
# [1] "Displacement (disp)"