# The seq Function in R: How to use seq() in R

The seq() function comes in handy in R when working with sequences, vectors, loops, etc. In this tutorial, we will show you syntax and then give detailed examples of popular situations that need to use the seq() function.

## What is the seq() function in R

The seq() function helps you create a customized sequence number used for columns’ value of data frames, elements of vectors or matrixes, or even in loops.

Syntax:

seq(start, end, by, length.out, along.with)

Arguments:

• start: A number assigned to the start point
• end: A number assigned to the endpoint
• by: A number greater than 1 assigned to step
• length.out: A number assigned to the length of the sequence
• along.with: Two numbers assigned to the length of the sequence

## How to use the seq() function?

If you want to use the function, you have to determine 4 parameters: the data frame’s name, that is, the data frame to apply the function, the key and value column’s name, and a range of columns to create the pair of key and value.

Below are some examples of using the seq() function.

### Create a sequence with the default step

If you want to create a sequence with steps equal to 1, you only need to specify the start and end points. For example, we will create a sequence from 1 to 9.

Code:

# Create a sequence from 1 to 9 with step = 1
mySeq = seq(1,9)

print("My sequence number is:")
print(mySeq)

Result:

[1] "My sequence number is:"
[1] 1 2 3 4 5 6 7 8 9

### Create a sequence with a step greater than 1

To create a sequence number with the difference between consecutive numbers greater than 1, you must pass the value to the parameter “by”. For example, we will create a sequence of even numbers from 0 to 10.

Code:

# Create a sequence of even numbers
evenNumber = seq(0,10, by=2)

print("My sequence of even number is:")
print(evenNumber)

Result:

[1] "My sequence of even number is:"
[1] 0 2 4 6 8 10

### Create a sequence with a fixed length

In some cases, you want to create a sequence with a fixed length; for example, if the length is 6, you must pass 6 as the value of the “length.out” parameter. This way, you only need to determine the start and end points. The function will automatically calculate the step between numbers.

Code:

# Create a sequence of length 6
mySeq = seq(0,20, length.out=6)

print("My sequence of length six is:")
print(mySeq)

Result:

[1] "My sequence of length six is:"
[1] 0 4 8 12 16 20

### Create a sequence with a length from x to y

When you pass two values: x and y, to the along.with parameter, you can create a sequence of length equal to the length from x to y. In this way, you also need to determine the start and endpoint.

Code:

# Create a sequence of length equal to the length from 6 to 10
mySeq = seq(0,20, along.with = 6:10)

print("My sequence is:")
print(mySeq)

Result:

[1] "My sequence is:"
[1] 0 5 10 15 20

## Summary

In summary, by providing values to the function’s parameter, you can use the seq() function to create a sequence number with a fixed step of a fixed length. We hope this article is helpful for you. Thanks for reading!

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