Selection of data frame elements
Similar to vectors and matrices, you select elements from a data frame with the help of square brackets [ ]. By using a comma, you can indicate what to select from the rows and the columns respectively. For example:
my_df[1,2]selects the value at the first row and second column inmy_df.my_df[1:3,2:4]selects rows 1, 2, 3 and columns 2, 3, 4 inmy_df.
Sometimes you want to select all elements of a row or column. For example, my_df[1, ] selects all elements of the first row. Let us now apply this technique on planets_df!
This is a part of the course
“Introduction to R”
Exercise instructions
- From
planets_df, select the diameter of Mercury: this is the value at the first row and the third column. Simply print out the result. - From
planets_df, select all data on Mars (the fourth row). Simply print out the result.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# The planets_df data frame from the previous exercise is pre-loaded
# Print out diameter of Mercury (row 1, column 3)
# Print out data for Mars (entire fourth row)