# How to convert matrix columns to a list of vectors in R?

If we want to use columns of a matrix as a vector then we can convert them in a list of vectors. To convert matrix columns to a list of vectors, we first need to convert the matrix to a data frame then we can read it as list. This can be done as as.list(as.data.frame(matrix_name)).

## Example

Consider the below matrix −

> M<-matrix(1:25,nrow=5)
> M
[,1] [,2] [,3] [,4] [,5]
[1,] 1 6 11 16 21
[2,] 2  7 12 17 22
[3,] 3  8 13 18 23
[4,] 4  9 14 19 24
[5,] 5 10 15 20 25

Converting matrix M columns to vectors −

> V<-as.list(as.data.frame(M))
> V
$V1 [1] 1 2 3 4 5$V2
[1] 6 7 8 9 10
$V3 [1] 11 12 13 14 15$V4
[1] 16 17 18 19 20
$V5 [1] 21 22 23 24 25 > str(V) List of 5$ V1: int [1:5] 1 2 3 4 5
$V2: int [1:5] 6 7 8 9 10$ V3: int [1:5] 11 12 13 14 15
$V4: int [1:5] 16 17 18 19 20$ V5: int [1:5] 21 22 23 24 25

Checking whether V1, V2, V3, V4, and V5 are vectors or not −

> is.vector(V$V1) [1] TRUE > is.vector(V$V2)
[1] TRUE
> is.vector(V$V3) [1] TRUE > is.vector(V$V4)
[1] TRUE
> is.vector(V$V5) [1] TRUE Converting non-square matrix columns to vector list − > M_new<-matrix(1:50,nrow=5) > M_new [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [1,] 1 6 11 16 21 26 31 36 41 46 [2,] 2 7 12 17 22 27 32 37 42 47 [3,] 3 8 13 18 23 28 33 38 43 48 [4,] 4 9 14 19 24 29 34 39 44 49 [5,] 5 10 15 20 25 30 35 40 45 50 > V_new<-as.list(as.data.frame(M_new)) > V_new$V1
[1]  1  2  3  4  5
$V2 [1] 6 7 8 9 10$V3
[1] 11 12 13 14 15
$V4 [1] 16 17 18 19 20$V5
[1] 21 22 23 24 25
$V6 [1] 26 27 28 29 30$V7
[1] 31 32 33 34 35
$V8 [1] 36 37 38 39 40$V9
[1] 41 42 43 44 45
\$V10
[1] 46 47 48 49 50
Published on 11-Aug-2020 07:41:37
Advertisements