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:
To create a vector with numerical values in a sequence, use the : operator:
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 5.5In 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:
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 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:
To make bigger or smaller steps in a sequence, use the seq() function:
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.
