Difference between revisions of "R/C2/Lists-and-its-Operations/English-timed"

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Latest revision as of 18:07, 1 June 2020

Time Narration
00:01 Welcome to the spoken tutorial on Lists and its Operations.
00:06 In this tutorial, we will learn how to:
00:11 Create a list in R
00:14 Access the elements of a list
00:18 Perform indexing on lists
00:21 Combine two lists
00:25 To understand this tutorial, you should know,
00:28 Data frames in R
00:31 Matrices and vectors in R
00:35 If not, please locate the relevant tutorials on R on this website.
00:42 This tutorial is recorded on
00:45 Ubuntu Linux OS version 16.04
00:51 R version 3.4.4
00:55 RStudio version 1.1.456
01:00 Install R version 3.2.0 or higher.
01:06 For this tutorial, we will use,
01:10 A data frame CaptaincyData.csv
01:15 and A script file myList.R.
01:20 Please download these files from the Code files link of this tutorial.
01:26 I have downloaded and moved these files to Lists folder.
01:32 This folder is located in myProject folder on my Desktop.
01:38 I have also set this folder as my Working Directory.
01:44 Let us switch to RStudio.
01:47 Open the script myList.R in RStudio.
01:53 I am resizing the Source window
01:58 Run this script by clicking on Source button.
02:02 captaincy data frame opens in the Source window.
02:07 Now let us create a matrix from a subset of captaincy.
02:13 We will convert the values in first three rows of played, won and lost columns into a matrix.
02:23 Click on the script myList.R
02:27 In the Source window, type the following commands.
02:31 Press Enter.
02:33 Press Enter at the end of every command.
02:37 Remember, as.matrix function is used to convert subData into a matrix.
02:45 Now let us create a numeric vector myVector.
02:51 In the Source window, type the following command.
02:54 Save the script and run the last three lines of code by pressing Ctrl + Enter keys simultaneously.


03:06 I am resizing the Source window
03:10 The three objects subData, matrixA and myVector are loaded in our workspace.
03:17 We will learn how to create a list in R by using the list function.
03:23 A list is an R object.
03:27 It has components of mixed data types like
03:33 strings
03:35 numbers
03:37 vectors
03:38 some other list inside it.
03:41 A list can also contain a matrix or a function as its elements.
03:48 A vector having all elements of the same type is called atomic vector,
03:56 whereas, A vector having elements of different types is called list.
04:02 Let us switch to RStudio.
04:05 We will create a list containing captaincy, matrixA and myVector.
04:13 I am resizing the Source window
04:18 In the Source window, type the following command.
04:21 Now, we will assign names to the elements of myList.
04:27 For this, we will use names function.
04:31 In the Source window, type the following command.
04:35 We will assign the following names,
04:40 dataframe to captaincy.
04:44 matrix to matrixA
04:47 vector to myVector
04:49 In the Source window, now type print, myList in parentheses.
04:55 Run the last three lines of code.
04:59 I am resizing the Console window.
05:03 In the Console window, three elements of myList are shown with their respective names.
05:11 Hence, myList is a named list.
05:15 Now, we will learn how to access the elements of a list.
05:21 I am resizing the Console window.
05:25 Elements of the list can be accessed by the index of the elements in the list.
05:32 It is also known as indexing.
05:35 In case of named lists, it can also be accessed by using the names.
05:43 Suppose we want to access the element named as dataframe of myList.
05:49 In the Source window, type myList dollar sign dataframe
05:56 Run the current line.
05:58 captaincy dataframe, which is an element of myList, is shown on the Console.
06:04 We can also access an element by using its index.
06:11 Suppose we want to access the element named matrix of myList.
06:17 Index of matrix is 2 in myList.
06:21 In the Source window, type myList and 2 in square brackets.
06:28 Run the current line.
06:31 matrix element of myList is shown on the Console.
06:36 Now, suppose we want to access the third column of matrix element of myList.
06:42 For this, we use double square brackets.
06:47 In the Source window, type the following command.
06:51 2 in double square brackets denotes that second element of myList is to be accessed.
07:00 comma 3 in single square brackets denotes that third column of second element is to be accessed.
07:08 Remember we use single square bracket notation with two indices for indexing a data frame.
07:17 First index and second index refer to row and column respectively.
07:23 Also, leaving an index blank indicates that we want to keep all the elements in that dimension.


07:31 Run the current line.
07:34 The elements of third column of matrix element are displayed on the Console.
07:40 Now, let us learn how to combine two different lists.
07:45 First, we will create a simple list.
07:49 In the Source window, type the following command.
07:53 Save the script and run the current line.
07:57 Now, we declare an object named merged dot list.
08:03 It is used for storing the combined output of myList and listSimple.
08:11 In the Source window, type the following commands.
08:15 Save the script and run the last three lines of code.
08:20 I am maximizing the Console window.
08:24 Now, scroll up to locate the output.
08:28 The combined list is shown on the Console.
08:33 Let us summarize what we have learnt.
08:37 In this tutorial, we have learned how to
08:41 Create a list in R
08:43 Access the elements of a list
08:46 Perform indexing on lists
08:50 Combine two lists
08:53 We now suggest an assignment.
08:56 Create a numeric vector c(1:5) and a 5 by 3 matrix with elements from 1 to 15.
09:04 Create a named list with vector, matrix and iris data set.
09:11 Retrieve the iris data set from the list using dollar operator and indexing method.
09:18 State the differences between the results obtained by using dollar operator and indexing method of accessing iris.
09:28 For solutions, please refer to the Additional Material section on this website.
09:35 The video at the following link summarises the Spoken Tutorial project.
09:41 Please download and watch it.
09:44 We conduct workshops using Spoken Tutorials and give certificates.
09:49 Please contact us.
09:52 Please post your timed queries in this forum.
09:57 Please post your general queries in this forum.
10:01 The FOSSEE team coordinates the TBC project.
10:05 For more details, please visit these sites.
10:08 The Spoken Tutorial project is funded by NMEICT, MHRD, Govt. of India
10:15 The script for this tutorial was contributed by Shaik Sameer (FOSSEE Fellow 2018).
10:22 This is Sudhakar Kumar from IIT Bombay signing off. Thanks for watching.

Contributors and Content Editors

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