Sakinashaikh at 10:56, 5 June 2020

2020-06-05T10:56:09Z

Sakinashaikh at 10:10, 22 May 2020

2020-05-22T10:10:11Z

Sakinashaikh at 10:09, 22 May 2020

2020-05-22T10:09:51Z

Sakinashaikh at 10:09, 22 May 2020

2020-05-22T10:09:23Z

Sakinashaikh at 10:08, 22 May 2020

2020-05-22T10:08:01Z

Sakinashaikh at 10:07, 22 May 2020

2020-05-22T10:07:20Z

Sakinashaikh: Created page with " {|border=1 ||'''Time''' ||'''Narration''' |- || || |- || 00:01 || Welcome to the spoken tutorial on '''Indexing and Slicing Data Frames'''. |- || 00:08 || In this tu..."

2020-05-22T10:06:49Z

Created page with " {|border=1 ||'''Time''' ||'''Narration''' |- || || |- || 00:01 || Welcome to the spoken tutorial on '''Indexing and Slicing Data Frames'''. |- || 00:08 || In this tu..."

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{|border=1
||'''Time'''
||'''Narration'''

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||

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|| 00:01
|| Welcome to the spoken tutorial on '''Indexing and Slicing Data Frames'''.

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|| 00:08
|| In this tutorial, we will learn how to:

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|| 00:12
|| Extract '''rows''' or '''columns''' from a '''data '''frame

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|| 00:17
|| Create a '''subset''' from a''' data frame'''

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|| 00:21
|| Retrieve '''data '''using double square brackets

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|| 00:25
|| To understand this tutorial, you should have knowledge about

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|| 00:30
|| '''Data frames''' in''' R'''

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|| 00:33
|| '''R''' '''script '''in '''RStudio '''and

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|| 00:37
|| How to set '''Working directory''' in''' RStudio'''

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|| 00:41
|| If not, please locate the relevant tutorials on '''R''' on this website.

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|| 00:48
|| This tutorial is recorded on

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|| 00:52
|| '''Ubuntu Linux '''OS version''' 16.04'''

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|| 00:57
|| '''R '''version''' 3.2.3'''

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|| 01:01
|| '''RStudio''' version''' 1.1.456'''

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|| 01:07
|| Install '''R''' version '''3.2.0''' or higher.

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|| 01:14
|| For this tutorial, we will use the '''data frame CaptaincyData.csv''' and a '''script '''file '''mydataframe.R'''.

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|| 01:25
|| Download these files from the '''Code files''' link of this tutorial.

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|| 01:31
|| I have downloaded and moved these files to the folder '''myProject''' on my '''Desktop'''.

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|| 01:39
|| I have also set this folder as my '''Working Directory.'''

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|| 01:45
||Let us switch to '''Rstudio'''.

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|| 01:48
|| Let us open the '''script mydataframe.R''' in '''RStudio.'''

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|| 01:55
|| For this, click on the '''script mydataframe.R'''.

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|| 02:01
|| '''Script mydataframe.R '''opens in '''Rstudio.'''
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|| 02:07
|| Here, we have declared a''' variable captaincy''' to store and read '''CaptaincyData.csv'''.

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|| 02:16
|| Also, '''View function''' is being used to see the contents of the file.

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|| 02:23
|| Remember, you may also use '''equal''' to sign in place of '''less than''' symbol followed by '''hyphen'''.

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|| 02:32
|| However, we recommend '''less than''' symbol followed by '''hyphen'''.

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|| 02:38
|| For this, there is a shortcut in '''RStudio'''.

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|| 02:42
|| Suppose we want to assign a value of 2 to a variable named '''testvar'''.

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|| 02:49
|| In the '''Console''' window, type '''testvar''' and then press

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|| 02:54
|| ''Alt '''and '''-'''('''hyphen''')''' '''keys simultaneously.

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|| 02:58
|| Then type 2 and press '''Enter'''.

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|| 03:01
|| Let us get back to the '''Source''' window.

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|| 03:06
|| Run the '''script''' '''mydataframe.R''' by clicking on the '''Source''' button.

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|| 03:13
|| Now let us extract the contents of the third row of the '''captaincy data frame'''.

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|| 03:20
|| Click on '''script''' '''mydataframe.R'''
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|| 03:25
|| In the '''Source '''window, type '''captaincy '''

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|| 03:29
|| Type '''capt''' and press '''Enter '''to make the variable '''captaincy '''autocomplete. Now''' '''within square brackets 3 followed by '''comma. '''And press '''Enter'''.

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|| 03:47
|| Press '''Enter '''key''' '''at the end of every command.

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|| 03:51
|| Remember one of the most important features of '''RStudio''' include intelligent auto-completion of function names, packages, and R objects.

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|| 04:04
|| We use a '''comma''' within square brackets when we wish to extract a '''row'''.

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|| 04:11
|| Save the '''script '''and execute the current line by pressing '''Ctrl+Enter''' keys.

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|| 04:20
|| The third row of the '''captaincy data frame''' is seen in the '''Console''' window.

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|| 04:26
|| Now, let us run the same '''command''' without a '''comma'''.

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|| 04:31
|| In the '''Source '''window, type '''captaincy '''then''' '''within square brackets 3'''. '''

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|| 04:39
|| Save the '''script '''and run this line only, as shown earlier.

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|| 04:46
|| The contents of the third '''column''' of the '''data frame, '''are displayed on the '''Console '''window.

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|| 04:54
|| So, to extract a '''column''', we shouldn’t use a '''comma''' within the square brackets.

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|| 05:01
|| When we extract '''data''' using row number or column number, it is known as numeric indexing.

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|| 05:09
|| In the '''Source '''window, click on the '''captaincy data frame'''.

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|| 05:14
|| Let us now extract the contents of second and third '''rows''' of the '''captaincy''' '''data frame'''.

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|| 05:22
|| To retrieve more than one '''row''', we use a numeric '''index vector'''. Click on the '''script mydataframe.R'''

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|| 05:32
|| In the '''Source''' window, type the following command and press '''Enter'''.

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|| 05:38
|| '''c''' '''function '''is being used to concatenate the second and third '''rows'''.

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|| 05:45
|| Save the''' script''' and execute the current line.

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|| 05:51
|| The second and third '''rows''' of '''captaincy data frame''' are seen in the '''Console''' window.

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|| 05:58
|| In the '''Source '''window, click on the '''captaincy data frame'''.

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|| 06:03
|| Now, we’ll find who has played 25 matches from the '''played''' column of '''captaincy data frame'''.

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|| 06:12
|| Extracting this type of information is known as logical indexing.

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|| 06:19
|| Click on the '''script mydataframe.R'''

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|| 06:23
|| In the '''Source '''window, type '''captaincy'''
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|| 06:27
|| Within square brackets '''captaincy '''dollar sign '''played '''equal to equal to 25 '''comma. '''Press '''Enter'''.

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|| 06:38
|| Remember, '''dollar''' sign allows you to extract '''elements''' by name.

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|| 06:44
|| Please note that there is no space between the two equal to signs.

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|| 06:50
|| Save the '''script''' and execute the current line.

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|| 06:55
|| The details of '''captain Dravid '''are shown in the '''Console''' window.

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|| 07:01
|| In the '''Source '''window, click on the '''captaincy data frame'''.

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|| 07:06
|| Now let us learn how to get the values of any particular '''attribute''' for all the players.

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|| 07:14
|| We will fetch the '''names '''of all the captains.

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|| 07: 18
|| For this, we need to know the values in the first '''column'''.

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|| 07:23
|| Click on the '''script mydataframe.R'''

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|| 07:28
|| In the '''Source '''window, type '''captaincy '''and''' '''within square brackets '''1'''.

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||07:35
|| Please note that I have not used a '''comma''' inside the square brackets.

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|| 07:41
|| Save the '''script''' and execute the current line.
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|| 07:46
|| The '''names''' of the captains are seen in the '''Console''' window.

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|| 07:51
|| Usually we use column '''names''' instead of column numbers.

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|| 07:57
|| To know the names of the captains, type '''captaincy. '''

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|| 08:01
|| Within square brackets inside double quotes '''names'''

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|| 08:07
|| Save the '''script''' and execute the current line.

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|| 08:12
|| Names of the captains are shown in the '''Console''' window.

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|| 08:17
|| Extracting '''data''' by column names is known as name indexing.

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|| 08:23
|| Clear the '''Console''' window by clicking on the broom icon.

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|| 08:28
|| In the '''Source '''window, click on the '''captaincy data frame'''

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|| 08:33
|| Now let us view the names of the captains along with the number of matches they have won.

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|| 08:40
|| Click on the '''script mydataframe.R'''

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|| 08:44
|| In the '''Source '''window, type the following command and press '''Enter'''.

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|| 08:52
|| Here''' c''' '''function '''is used''' '''to concatenate '''names '''and '''won'''.

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|| 08:59
|| Observe that''' names''' and '''won''' have been written within double quotes.

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|| 09:06
|| Save the '''script''' and execute this line.

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|| 09:11
|| The '''names''' of captains and the number of matches '''won '''are seen in the '''Console''' window.

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|| 09:18
|| Now let us extract a '''subset '''from '''captaincy data frame'''.

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|| 09:24
|| We will create a '''subset''' of captains,''' '''who have won more than 30% of their matches.

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|| 09:32
|| This is called slicing a '''data frame'''.

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|| 09:36
|| In the '''Source '''window, click on the '''captaincy data frame'''.

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|| 09:41
|| Please note that there is a '''column''' named '''victory''' in the '''captaincy''' '''data frame.'''

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|| 09:48
|| For required '''subset '''of captains, their victory should be greater than 0.3.

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|| 09:55
|| For this '''subset''', we shall only show the

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|| 09:58
|| names

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|| 10:00
|| number of matches '''played'''

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|| 10:02
|| number of matches '''won'''

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|| 10:05
|| Click on the '''script mydataframe.R'''

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|| 10:09
|| I will resize the '''Source''' window.

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|| 10:13
|| In the '''Source '''window, type '''the following command'''

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|| 10:18
|| Now, press '''Enter '''after the comma followed by 0 point 3.

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|| 10:25
|| You can press '''Enter''' after a''' comma''' for better visibility.

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|| 10:30
|| The''' select parameter''' is used to select the required columns, '''names''', '''played''', and '''won'''.

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|| 10:38
|| In the '''Source '''window, type '''print''' within '''parentheses subData '''.

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|| 10:45
|| Save the '''script''' and run these two lines.

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|| 10:51
|| I am resizing the '''Console''' window to see the output properly.

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|| 10:57
|| The '''subData '''is shown in the '''Console''' window.

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|| 11:01
|| In the '''Source '''window, click on the '''captaincy data frame'''.

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|| 11:07
|| Finally, let us learn how to extract a particular entry from some '''column''' of a '''data frame'''.

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|| 11:16
|| We will extract the third value in the fourth '''column''' of the '''captaincy data frame'''.

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|| 11:23
|| Click on the '''script mydataframe.R'''.

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|| 11:26
|| In the '''Source '''window, type '''captaincy '''within double square brackets '''4''' within single square brackets '''3'''.

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|| 11:37
|| Save the '''script''' and execute the current line.

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|| 11:42
|| The expected value''' 14''' is seen in the '''Console''' window.

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|| 11:48
|| For more information on '''indexing '''and '''slicing '''data frames, please refer to the '''Additional materials''' section on this website.

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|| 11:58
|| Let us summarize what we have learnt.

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|| 12:03
|| In this tutorial, we have learnt how to:

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|| 12:07
|| Extract rows or columns from a '''data frame'''

|-
|| 12:12
|| Create a '''subset''' from a '''data frame '''

|-
|| 12:16
|| Retrieve data using double square brackets

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|| 12:20
|| We now suggest an assignment.

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|| 12:24
|| Create a '''subset '''from '''captaincy data frame''' with the captains who have played more than(>) 20 matches and lost less than(<) 14 matches.

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|| 12:36
|| The video at the following link summarises the Spoken Tutorial project.

|-
|| 12:41
|| Please download and watch it.

|-
|| 12:44
|| We conduct workshops using Spoken Tutorials and give Certificates.

|-
|| 12:50
|| Please contact us.

|-
|| 12:53
|| Please post your timed queries in this forum.

|-
|| 12:57
|| Please post your general queries in this forum.

|-
|| 13:02
|| The '''FOSSEE '''team coordinates the '''TBC '''project.

|-
|| 13:06
|| For more details, please visit these sites.

|-
|| 13:10
|| The Spoken Tutorial project is funded by NMEICT, MHRD, Govt. of India

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|| 13:16
|| The script for this tutorial was contributed by Shaik Sameer (FOSSEE Fellow 2018).

|-
|| 13:24
|| This is Sudhakar Kumar from IIT Bombay signing off. Thanks for watching.

@@ Line 122: / Line 122: @@
 |-
 || 02:49
-|| In the '''Console''' window, type '''testvar''' and then press
+|| In the '''Console''' window, type '''testvar''' and then press '''Alt '''and '''-'''('''hyphen''')''' '''keys simultaneously.
-−
-|-
-|| 02:54
-|| ''Alt '''and '''-'''('''hyphen''')''' '''keys simultaneously.
 |-

@@ Line 5: / Line 5: @@
 ||'''Narration'''
 |-
 || 00:01

@@ Line 283: / Line 283: @@
 |-
-|| 07: 18
+|| 07:18
 || For this, we need to know the values in the first '''column'''.

@@ Line 504: / Line 504: @@
 || 12:24
 || Create a '''subset '''from '''captaincy data frame''' with the captains who have played more than(>) 20 matches and lost less than(<) 14 matches.
 |-

@@ Line 198: / Line 198: @@
 || 04:54
 || So, to extract a '''column''', we shouldn’t use a '''comma''' within the square brackets.
 |-

@@ Line 48: / Line 48: @@
 || 00:41
 || If not, please locate the relevant tutorials on '''R''' on this website.
 |-

R/C2/Indexing-and-Slicing-Data-Frames/English-timed - Revision history

Sakinashaikh at 10:56, 5 June 2020

Sakinashaikh at 10:10, 22 May 2020

Sakinashaikh at 10:09, 22 May 2020

Sakinashaikh at 10:09, 22 May 2020

Sakinashaikh at 10:08, 22 May 2020

Sakinashaikh at 10:07, 22 May 2020

Sakinashaikh: Created page with " {|border=1 ||'''Time''' ||'''Narration''' |- || || |- || 00:01 || Welcome to the spoken tutorial on '''Indexing and Slicing Data Frames'''. |- || 00:08 || In this tu..."