stringr::str_c()

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

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)"

See Also

• stringr::str_detect
• stringr::str_replace
• purrr::map