c()

c(..., recursive = FALSE, USE.NAMES = TRUE)

The c() function (short for “combine” or “concatenate”) is the most fundamental function in R for creating vectors. Almost every R script uses c() to group values together into a single vector. Understanding how c() works is essential for effective R programming.

Parameters

Parameter	Type	Default	Description
...	objects	required	Values to combine. Can be vectors, lists, or individual values.
recursive	logical	FALSE	If TRUE, recursively flattens lists into vectors.
USE.NAMES	logical	TRUE	If TRUE and the arguments are named, result inherits those names.

Return Value

When recursive = FALSE (default): returns a vector of the same type as the input (or the highest type in the coercion hierarchy: NULL < raw < logical < integer < double < complex < character)

When recursive = TRUE: returns a flattened vector, unlisting all nested structures

Type Coercion

R automatically coerces elements to the most flexible type:

# Numeric and character: all become character
c(1, 2, "three")
# [1] "1" "2" "three"

# Integer and numeric: all become numeric
c(1L, 2.5)
# [1] 1.0 2.5

# Mixed logical and numeric: logical TRUE/FALSE becomes 1/0
c(TRUE, 0, 1)
# [1] 1 0 1

Examples

Creating Basic Vectors

# Numeric vector
nums <- c(1, 2, 3, 4, 5)
nums
# [1] 1 2 3 4 5

# Character vector
words <- c("apple", "banana", "cherry")
words
# [1] "apple"  "banana" "cherry"

# Logical vector
flags <- c(TRUE, FALSE, TRUE, TRUE)
flags
# [1]  TRUE FALSE  TRUE  TRUE

Combining Vectors

# Concatenate two vectors
a <- c(1, 2, 3)
b <- c(4, 5, 6)
c(a, b)
# [1] 1 2 3 4 5 6

# Append single value to vector
c(a, 7)
# [1] 1 2 3 4 5 6 7

# Prepend value
c(0, a)
# [1] 0 1 2 3

Using recursive = TRUE

# List with nested vectors
my_list <- list(a = c(1, 2), b = c(3, 4))

# Default (recursive = FALSE) returns a list
c(my_list, recursive = FALSE)
# $a
# [1] 1 2
# $b
# [1] 3 4

# recursive = TRUE flattens to vector
c(my_list, recursive = TRUE)
# a1 a2 b1 b2 
#  1  2  3  4

Named Vectors

# Automatic naming with USE.NAMES = TRUE (default)
c(a = 1, b = 2, c = 3)
# a b c 
# 1 2 3 

# Disable naming
c(a = 1, b = 2, c = 3, USE.NAMES = FALSE)
# [1] 1 2 3

Common Use Cases

Building Data Frame Columns

df <- data.frame(
  name = c("Alice", "Bob", "Charlie"),
  age = c(25, 30, 35),
  score = c(85.5, 92.0, 78.5)
)

Vector Initialization

# Create empty vector
empty <- c()

# Pre-allocate with NA
initialized <- c(rep(NA, 10))

Combining Different Types (Caution!)

# This coerces everything to character
mixed <- c(1, "two", 3)
# [1] "1"  "two" "3"

# Check the type
typeof(mixed)
# [1] "character"

See Also

• seq()
• rep()
• sample()