# Create Matrix and Data Frame from Lists in R Programming

In R programming, there 5 basic objects. Lists are the objects that can contain heterogeneous types of elements, unlike vectors. Matrices can contain the same type of elements or homogeneous elements. On the other hand, data frames are similar to matrices but have an advantage over matrices to keep heterogeneous elements. In this article, we’ll learn to create matrix and data frame using lists.

#### Create Matrix using List

Matrices are created using `matrix()` function in R programming. Another function that will be used is `unlist()` function to convert the lists into a vector. The vector created contains atomic components of the given list.

Syntax:
unlist(x, recursive = TRUE, use.names = TRUE)

Parameters:

x: represents list
recursive: represents logical value. If FALSE, function will not recurse beyond first level of list
use.names: represents logical value to preserve the naming information

Example 1:

 `# Defining list ` `ls1 <``-` `list``( ` `  ``list``(``1``, ``2``, ``3``), ` `  ``list``(``4``, ``5``, ``6``)) ` ` `  `# Print list ` `cat(``"The list is:\n"``) ` `print``(ls1) ` `cat(``"Class:"``, ``class``(ls1), ``"\n"``) ` ` `  `# Convert list to matrix ` `mt1 <``-` `matrix(unlist(ls1), nrow ``=` `2``, byrow ``=` `TRUE) ` ` `  `# Print matrix ` `cat(``"\nAfter conversion to matrix:\n"``) ` `print``(mt1) ` `cat(``"Class:"``, ``class``(mt1), ``"\n"``) `

Output:

```The list is:
[[1]]
[[1]][[1]]
[1] 1

[[1]][[2]]
[1] 2

[[1]][[3]]
[1] 3

[[2]]
[[2]][[1]]
[1] 4

[[2]][[2]]
[1] 5

[[2]][[3]]
[1] 6

Class: list

After conversion to matrix:
[, 1] [, 2] [, 3]
[1, ]    1    2    3
[2, ]    4    5    6

Class: matrix ```

Example 2:

 `# Defining list ` `ls2 <``-` `list``(``"A"``, ``10``, TRUE, ``2i``) ` ` `  `# Print list ` `cat(``"\nThe list is:\n"``) ` `print``(ls2) ` `cat(``"Class:"``, ``class``(ls2), ``"\n"``) ` ` `  `# Convert list to matrix ` `mt2 <``-` `matrix(unlist(ls2), nrow ``=` `2``, byrow ``=` `TRUE) ` ` `  `# Print matrix ` `cat(``"\nAfter conversion to matrix:\n"``) ` `print``(mt2) ` `cat(``"Class:"``, ``class``(mt2), ``"\n"``) ` `cat(``"\nType:"``, typeof(mt2), ``"\n"``) `

Output:

```The list is:
[[1]]
[1] "A"

[[2]]
[1] 10

[[3]]
[1] TRUE

[[4]]
[1] 0+2i

Class: list

After conversion to matrix:
[, 1]   [, 2]
[1, ] "A"    "10"
[2, ] "TRUE" "0+2i"

Class: matrix

Type: character```

#### Create Dataframe using List

In the same way, dataframe can be created using lists by using `unlist()` function and `data.frame()` function.

Example:

 `# Defining lists ` `n <``-` `list``(``1``:``3``) ` `l <``-` `list``(letters[``1``:``3``]) ` `m <``-` `list``(month.name[``1``:``3``]) ` ` `  `# Convert lists into dataframe columns ` `df <``-` `data.frame(unlist(n), unlist(l), unlist(m)) ` ` `  `# Names of columns of dataframe ` `names(df) <``-` `c(``"Number"``, ``"Letters"``, ``"Month"``) ` ` `  `# Print dataframe ` `cat(``"The dataframe is :\n"``) ` `print``(df) `

Output:

```The dataframe is :
Number Letters    Month
1      1       a  January
2      2       b February
3      3       c    March```

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