Indexing Method to Indicate Variables

Could we use the indexing method to indicate variables?

We can use the indexing numbers to refer to variables in a dataset. To do so, we first use the names() function to find the indexing numbers for relevant variables, and then we can refer to them in other functions. The following is an example of how to choose country, year, and rgdpl from the pwt7 dataset.

Note that based on the output for names() function, the number inside the brackets is the indexing number for the variable right next to it.

In this case below, country is in the first column, year in the third column, and rgdpl in the 24th column. So the two lines of code produce the same output.