## When should you use an R Matrix instead of a Data Frame?

a) When you need a two-dimensional structure with elements of the same type

b) When you need to store data of different types in a two-dimensional structure

c) When you need to store data in a single dimension

d) When you need to create a hierarchical data structure

### Answer:

a) When you need a two-dimensional structure with elements of the same type

### Explanation:

An R matrix should be used when you need a two-dimensional structure where all elements are of the same type, such as all numeric or all character data. Matrices are particularly useful in mathematical computations, such as matrix operations, where uniform data types are required.

```
# Creating a numeric matrix
my_matrix <- matrix(1:6, nrow = 2, ncol = 3)
# Printing the matrix
print(my_matrix)
# Output:
# [,1] [,2] [,3]
# [1,] 1 3 5
# [2,] 2 4 6
```

In this example, the matrix `my_matrix`

stores numeric data in a 2×3 grid. Since all elements are numeric, a matrix is an appropriate data structure. On the other hand, if you need to store different types of data (e.g., numbers, strings, factors) in a two-dimensional structure, a data frame would be more suitable.