Convert Vector to list and List to Vector in R

Hello, readers! In this article, we will be focusing convert vector to list and list to vector in R programming, in detail.

So, let us begin!

To begin with, vectors are the simplest form of data structure available in R. They store simple elements of the same data type in a single dimension in R programming.

Unlike vectors, lists can hold elements of varied data types in the form of multi dimensional schema.

Let us now have a look at the functions that would help us achieve the inter conversion of vectors and lists in R.

1. Conversion of List to Vector in R using unlist() function

In order to convert a vector to a list, R provides us with unlist() function that converts the list into a vector in R.

The unlist() function dissolves the list structure fed to it as arguments i.e. it converts the multi-dimensional schema into a a single dimensional schema.

Syntax:

unlist(list, use.names=True)

• use.names: If set to True(default), it preserves the names of the headers of the data values and represents the same in the output vector.

Example 01:

In this example, we have created a list with the headers ‘roll’ and ‘age’. After which, we have applied unlist() function to convert the list into a vector.

rm(list = ls())

lst <- list(roll = c(2,4,6,8,10),				 
                Age = c(15,6,1,12,13)) 


print(unlist(lst))									 

Output:

As seen below, the headers of the list are also displayed in the vector. This is because, the default value of use.names = True. Thus, in order to neglect the headers, we need to change it to False as shown in the next example.

roll1 roll2 roll3 roll4 roll5  Age1  Age2  Age3  Age4  Age5 
    2     4     6     8    10    15     6     1    12    13

Example 02:

In this example, we have set use.names = False. By this, we specific to ignore the header values and choose only the data values for the conversion.

rm(list = ls())

lst <- list(roll = c(2,4,6,8,10),				 
                Age = c(15,6,1,12,13)) 


print(unlist(lst,use.names = FALSE))									 

Output:

 2  4  6  8 10 15  6  1 12 13

2. Conversion of Vector to List using as.list() function in R

To convert a vector to list, R provides us with as.list() function that enables us to convert the single dimensional vector structure into a list format.

Have a look at the below syntax!

as.list(object)

Yes! The as.list() function can also be used to convert other data objects such as data frames, factors, matrices, etc to a list schema.

Example 01:

In the below example, we have created a single dimensional vector using c() function. Further, using as.list() function, we convert the vector to list form.

rm(list = ls())
vectr = c(10,20,30,40,50)
lst = as.list(vectr)
print(lst)

Output:

[[1]]
[1] 10

[[2]]
[1] 20

[[3]]
[1] 30

[[4]]
[1] 40

[[5]]
[1] 50

Example 02:

In this example, we have created a 4 by 4 matrix using matrix() function. Further, we have converted the matrix into a list using as.list() function successfully!

rm(list = ls())

data <- matrix(c(1,3,5,7,9,2,6,8), 4, 4) 
print("Matrix:")
print(data)

lst = as.list(data)
print("List:")
print(lst)

Output:

[1] "Matrix:"

     [,1] [,2] [,3] [,4]
[1,]    1    9    1    9
[2,]    3    2    3    2
[3,]    5    6    5    6
[4,]    7    8    7    8

[1] "List:"
[[1]]
[1] 1

[[2]]
[1] 3

[[3]]
[1] 5

[[4]]
[1] 7

[[5]]
[1] 9

[[6]]
[1] 2

[[7]]
[1] 6

[[8]]
[1] 8

[[9]]
[1] 1

[[10]]
[1] 3

[[11]]
[1] 5

[[12]]
[1] 7

[[13]]
[1] 9

[[14]]
[1] 2

[[15]]
[1] 6

[[16]]
[1] 8

Conclusion

By this, we have come to the end of this topic. Feel free to comment below, in case you come across any question.

For more such posts related to R programming, stay tuned with us.

Till then, Happy learning!! 🙂