View source for R/C2/Data-Manipulation-using-dplyr-Package/English-timed



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|'''Time'''
|'''Narration'''

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|| 00:01
|| Welcome to this tutorial on '''Data manipulation using '''dplyr package'''.

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|| In this tutorial, we will learn about,
 
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|| Data manipulation
 
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|| '''dplyr''' package

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|| How to use '''filter''' and '''arrange''' functions

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|| To understand this tutorial, you should know, 

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||  Basics of Statistics 

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||  Basics of '''ggplot2''' package

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||  Data frames 

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|| If not, please locate the relevant tutorials on '''R''' on this website.

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|| This tutorial is recorded on,

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||  '''Ubuntu Linux '''OS version '''16.04'''

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||  '''R''' version '''3.4.4'''

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|| '''RStudio''' version '''1.1.463'''

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|| Install '''R''' version '''3.2.0''' or higher. 

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|| For this tutorial, we will use

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||  A '''data frame moviesData.csv'''

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||  And A '''script''' file '''myVis.R'''.

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|| Please download these files from the '''Code files''' link of this tutorial. 

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|| I have downloaded and moved these files to '''DataVis''' folder. 

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|| This folder is located in '''myProject''' folder on my '''Desktop'''.

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|| I have also set '''DataVis''' folder as my '''Working Directory'''. 

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|| In real life, it is rare that we get the data in exactly the right form we need. 

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|| Often we’ll need to 

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||  create some new '''variables''' or '''summaries'''
 
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|| rename the '''variables'''
 
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|| reorder the observations in order to make the data a little easier to work with.

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|| We will learn how to achieve all this by using '''dplyr package'''.

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|| '''dplyr''' is a '''package''' for '''data manipulation''', written and maintained by '''Hadley Wickham'''.

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||  It comprises many '''functions''' that perform mostly used '''data manipulation operations'''. 

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|| Let us switch to '''RStudio'''.

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|| Open the '''script myVis.R '''in''' RStudio'''. 

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|| Let us '''run''' this '''script''' by clicking on the '''Source''' button. 

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|| '''movies data frame''' opens in the '''Source''' window. 

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|| This '''data frame''' will be used later in this tutorial. 

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|| Now, we will install '''dplyr package'''. Please make sure that you are connected to the '''Internet'''. 

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|| In the '''Console''' window, type the following '''command''' and press '''Enter'''. 

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|| The installation of the '''package''' takes a few seconds. 

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|| We will wait while the '''package''' is being installed. 

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|| To load this '''package''', we will add the library at the top of the '''script'''.

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|| Click on the '''script myVis.R'''

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|| At the top of the '''script''', type '''library''' and '''dplyr '''in parentheses.

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|| Save the '''script '''and '''run''' this line by pressing '''Ctrl + Enter''' keys simultaneously.

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|| Now we learn about some key '''functions''' in '''dplyr package''': 

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|| '''filter'''- to select ''cases'' based on their values. 

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|| '''arrange''' - to reorder the '''cases.''' 
 
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|| '''select''' - to select '''variables''' based on their names.
 
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|| '''mutate''' - to add new '''variables''' that are '''functions''' of existing '''variables'''.

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|| '''summarise''' - to condense multiple values to a single value.

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|| All these '''functions''' can be combined with '''group underscore by function'''. 

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|| It allows us to perform any operation by a '''group'''.

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|| Let us switch to '''RStudio'''.

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|| In the '''Source''' window, click on '''movies'''. 

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|| In the '''Source''' window, scroll from left to right. 

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|| This will enable us to see the remaining '''objects''' of '''movies data frame'''. 

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|| Suppose we want to filter the movies having genre as '''Comedy'''.

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|| For this, we will use the '''filter function'''. 

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|| Click on the '''script myVis.R'''

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|| In the '''Source''' window, type the following '''command'''. 

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|| Recall that, '''filter function''' in '''dplyr package''' allows us to select '''cases''' based on their values. 

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|| Inside the '''filter function''', the first '''argument''' is the name of the '''data frame''' which is '''movies'''. 

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|| The second '''argument''' is the value by which we want to filter the '''movies data frame. '''

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|| Save the '''script''' and '''run''' the current line. 

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|| Resulting '''data frame''' is stored in an '''object''' called '''moviesComedy''' in the''' Environment window.'''

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|| Let us view the '''data frame moviesComedy''' to check whether it contains '''movies''' with genre as '''Comedy'''.

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|| In the '''Source''' window, type the following '''command'''. 

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|| '''Run''' the current line. 

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|| '''moviesComedy data frame''' opens in the '''Source''' window. 

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|| All the '''movies''' having genre as '''Comedy''' have been filtered. 

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|| Let us close this '''data frame moviesComedy''' for now. 

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|| We can also use '''logical''' operators to combine two or more than two values. 

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|| In the '''Source''' window, click on '''movies'''. 

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|| Suppose we want to filter the '''movies''' with '''genre''' as either '''Comedy''' or '''Drama'''. 

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|| Click on the '''script myVis.R'''

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|| In the '''Source''' window, type the following '''commands'''. 

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|| Here, we have two values by which we would like to filter '''movies data frame'''. 

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|| For this, we have used a '''logical OR''' operator. 

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|| '''Run''' the last two lines of code. 

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|| '''moviesComDr '''opens in the '''Source''' window. 

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|| The '''movies''' having genre as either '''Comedy '''or '''Drama '''have been filtered. 

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|| Let us close this '''data frame moviesComDr''' for now. 

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|| This '''filter function''' can also be written using the '''match''' operator. 

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|| In the '''Source''' window, type the following '''command'''. 

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|| '''%in%''' is used for value matching. 

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|| To know more about this operator, let us access the '''Help'''. 

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|| In the '''Console''' window, type the following '''command''' and press '''Enter'''. 

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|| '''Run''' the last two lines of code. 

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|| '''moviesComDrP '''opens in the '''Source''' window. 

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|| The movies having genre as either '''Comedy '''or '''Drama '''have been filtered. 

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|| Let us close this '''data frame moviesComDrP '''for now. 

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|| In the '''Source''' window, click on '''movies'''. 

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|| In the '''Source''' window, scroll from left to right. 

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|| Let us now filter movies with genre as '''Comedy''' and '''imdb underscore rating '''greater than or equal to 7 point 5.

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|| Click on the '''script myVis.R'''

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|| In the '''Source''' window, type the following '''command'''. 

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|| Here, we have used a '''logical AND''' operator to include both conditions. 

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|| Save the script and '''run''' the last two lines of code. 

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|| '''moviesComIm''' opens in the '''Source''' window. 

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|| I will resize the '''Console''' window. 

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|| There are seven movies with genre as '''Comedy''' and '''imdb underscore rating''' greater than or equal to 7 point 5. 

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|| Let us close this '''data frame moviesComIm '''for now. 

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|| In the '''Source''' window, click on '''movies'''. 

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|| Suppose, we want to arrange the movies in an ascending order of '''imdb underscore rating'''. 

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|| For this, we will use the '''arrange function'''. 

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|| Click on the '''script myVis.R'''

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|| In the '''Source''' window, type the following '''command'''. 

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|| '''Run''' the last two lines of code. 

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|| '''moviesImA '''opens in the '''Source''' window. 

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|| In the '''Source''' window, scroll from left to right and locate the '''imdb underscore rating''' column. 

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|| The movies have been arranged in ascending order of '''imdb  rating'''. 

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|| Now, let us say we want to arrange the movies in descending order of''' imdb rating. '''

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|| For this, we use '''desc function'''. 

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|| Let us close this '''data frame moviesImA''' for now. 

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|| In the '''Source''' window, type the following '''command'''. 

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|| '''Run''' the last two lines of code. 

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|| '''moviesImD''' opens in the '''Source''' window. 

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|| In the '''Source''' window, scroll from left to right and locate the '''imdb underscore rating''' column. 

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|| The movies have been arranged in descending order of '''imdb rating'''. 

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|| Let us close this '''data frame moviesImD''' for now. 

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|| In the '''Source''' window, click on '''movies'''. 

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|| Suppose we want to arrange the movies both by genre and '''imdb rating'''.

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|| Click on the '''script myVis.R'''

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|| In the '''Source''' window, type the following '''commands'''. 

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|| '''Run''' the last two lines of code. 

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|| '''moviesGeIm''' opens in the '''Source''' window. 

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|| In the '''Source''' window, scroll from left to right. 

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|| Movies have been arranged both by genre and '''imdb  rating'''.

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|| Let us summarize what we have learnt.

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|| In this tutorial, we have learnt about:
 
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|| 12:23
|| '''Data manipulation'''
 
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|| 12:26
|| '''dplyr package'''

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||  How to use '''filter''' and '''arrange functions'''.

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|| 12:32
|| We now suggest an assignment.

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|| 12:36
||  Consider the '''built-in data set mtcars'''. Find the cars with '''hp''' greater than 100 and '''cyl''' equal to 3.

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|| 12:47
||  Arrange the '''mtcars data set '''based on '''mpg variable'''.

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|| 12:53
|| The video at the following link summarises the Spoken Tutorial project.

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|| 12:58
|| Please download and watch it.

|- 
|| 13:02
|| We conduct workshops using Spoken Tutorials and give certificates.

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|| 13:08
|| Please contact us.

|- 
|| 13:11
|| Please post your timed queries in this forum.

|- 
|| 13:16
|| Please post your general queries in this forum.

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|| 13:21
|| The '''FOSSEE '''team coordinates the '''TBC '''project.

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|| 13:24
|| For more details, please visit these sites.

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|| 13:29
|| The Spoken Tutorial project is funded by , MHRD, Govt. of India

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|| 13:36
|| The script for this tutorial was contributed by Varshit Dubey (CoE Pune).

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|| 13:44
|| This is Sudhakar Kumar from IIT Bombay signing off. Thanks for watching.