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R Vectors


Vectors

A vector is simply a list of items that are of the same type.

To combine the list of items to a vector, use the c() function and separate the items by a comma.

In the example below, we create a vector variable called fruits, that combine strings:

Example

# Vector of strings
fruits <- c("banana", "apple", "orange")

# Print fruits
fruits
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In this example, we create a vector that combines numerical values:

Example

# Vector of numerical values
numbers <- c(1, 2, 3)

# Print numbers
numbers
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To create a vector with numerical values in a sequence, use the : operator:

Example

# Vector with numerical values in a sequence
numbers <- 1:10

numbers
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You can also create numerical values with decimals in a sequence, but note that if the last element does not belong to the sequence, it is not used:

Example

# Vector with numerical decimals in a sequence
numbers1 <- 1.5:6.5
numbers1

# Vector with numerical decimals in a sequence where the last element is not used
numbers2 <- 1.5:6.3
numbers2

Result:

[1] 1.5 2.5 3.5 4.5 5.5 6.5
[1] 1.5 2.5 3.5 4.5 5.5
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In the example below, we create a vector of logical values:

Example

# Vector of logical values
log_values <- c(TRUE, FALSE, TRUE, FALSE)

log_values
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Vector Length

To find out how many items a vector has, use the length() function:

Example

fruits <- c("banana", "apple", "orange")

length(fruits)
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Sort a Vector

To sort items in a vector alphabetically or numerically, use the sort() function:

Example

fruits <- c("banana", "apple", "orange", "mango", "lemon")
numbers <- c(13, 3, 5, 7, 20, 2)

sort(fruits)  # Sort a string
sort(numbers) # Sort numbers
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Access Vectors

You can access the vector items by referring to its index number inside brackets []. The first item has index 1, the second item has index 2, and so on:

Example

fruits <- c("banana", "apple", "orange")

# Access the first item (banana)
fruits[1]
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You can also access multiple elements by referring to different index positions with the c() function:

Example

fruits <- c("banana", "apple", "orange", "mango", "lemon")

# Access the first and third item (banana and orange)
fruits[c(1, 3)]
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You can also use negative index numbers to access all items except the ones specified:

Example

fruits <- c("banana", "apple", "orange", "mango", "lemon")

# Access all items except for the first item
fruits[c(-1)]
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Change an Item

To change the value of a specific item, refer to the index number:

Example

fruits <- c("banana", "apple", "orange", "mango", "lemon")

# Change "banana" to "pear"
fruits[1] <- "pear"

# Print fruits
fruits
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Repeat Vectors

To repeat vectors, use the rep() function:

Example

Repeat each value:

repeat_each <- rep(c(1,2,3), each = 3)

repeat_each
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Example

Repeat the sequence of the vector:

repeat_times <- rep(c(1,2,3), times = 3)

repeat_times
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Example

Repeat each value independently:

repeat_indepent <- rep(c(1,2,3), times = c(5,2,1))

repeat_indepent
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Generating Sequenced Vectors

One of the examples on top, showed you how to create a vector with numerical values in a sequence with the : operator:

Example

numbers <- 1:10

numbers
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To make bigger or smaller steps in a sequence, use the seq() function:

Example

numbers <- seq(from = 0, to = 100, by = 20)

numbers
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Note: The seq() function has three parameters: from is where the sequence starts, to is where the sequence stops, and by is the interval of the sequence.