Selecting elements from a list
Your list will often be built out of numerous elements and components. Therefore, getting a single element, multiple elements, or a component out of it is not always straightforward.
One way to select a component is using the numbered position of that component. For example, to "grab" the first component of shining_list you type
shining_list[[1]]
A quick way to check this out is typing it in the console. Important to remember: to select elements from vectors, you use single square brackets: [ ]. Don't mix them up!
You can also refer to the names of the components, with [[ ]] or with the $ sign. Both will select the data frame representing the reviews:
shining_list[["reviews"]]
shining_list$reviews
Besides selecting components, you often need to select specific elements out of these components. For example, with shining_list[[2]][1] you select from the second component, actors (shining_list[[2]]), the first element ([1]). When you type this in the console, you will see the answer is Jack Nicholson.
This is a part of the course
“Introduction to R”
Exercise instructions
- Select from
shining_listthe vector representing the actors. Simply print out this vector. - Select from
shining_listthe second element in the vector representing the actors. Do a printout like before.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# shining_list is already pre-loaded in the workspace
# Print out the vector representing the actors
# Print the second element of the vector representing the actorsThis exercise is part of the course
Introduction to R
Master the basics of data analysis in R, including vectors, lists, and data frames, and practice R with real data sets.
As opposed to vectors, lists can hold components of different types, just as your to-do lists can contain different categories of tasks. This chapter will teach you how to create, name, and subset these lists.
Exercise 1: Lists, why would you need them?Exercise 2: Lists, why would you need them? (2)Exercise 3: Creating a listExercise 4: Creating a named listExercise 5: Creating a named list (2)Exercise 6: Selecting elements from a listExercise 7: Creating a new list for another movieWhat is DataCamp?
Learn the data skills you need online at your own pace—from non-coding essentials to data science and machine learning.