Introduction to data frames
Data frame structure
6. Column names
Accessing columns in a data frame
Accessing rows of a data frame
Accessing rows and columns combined in a data frame
Data frame analysis


Great! With nrow() and ncol(), you can tell how big your data frame is. One important function that allows you to familiarize yourself with a data frame is the names() function. This function takes a data frame and displays the names of all of its columns. So, if you make a call to

R will print a character vector:

[1] "country" "city" "latitude" "longitude" "population"

The length of this vector is 5 because we have 5 columns in the cities data frame.


Display the column names of the countries data frame.