Course Content

# R Introduction: Part I

R Introduction: Part I

## Indexing

Great! You now understand how to create a vector and how to assign names to its values.

To access a specific element or elements within a vector, you can utilize indices. The index of the first element is 1, the second element is 2, and so on. To retrieve the `n`-th element from a vector `vec`, the syntax is `vec[n]`. Moreover, if the vector elements have assigned names, you can extract the values by their names by enclosing the name in quotes and square brackets.

Now, let’s revisit the grades example.

 Subject Grade Math 80 Physics 75 English 95 Literature 100

We’ll extract the grade for Math and the grade for Literature.

It’s also possible to access multiple elements simultaneously.

Continuing from the previous exercise, you have a vector named `prices` with each price assigned to a corresponding item name.
1. Retrieve the price of `'Armchair'` using its name rather than its index.
2. Retrieve the prices for both the `'Dining table'` and `'Dining chair'` using their indices.