Sakinashaikh at 13:31, 1 June 2020

2020-06-01T13:31:12Z

Sakinashaikh at 13:30, 1 June 2020

2020-06-01T13:30:50Z

Sakinashaikh at 13:30, 1 June 2020

2020-06-01T13:30:19Z

Sakinashaikh at 13:28, 1 June 2020

2020-06-01T13:28:54Z

Sakinashaikh: Created page with "{| border =1 |'''Time''' |'''Narration''' |- || 00:00 || Welcome to this tutorial on '''Functions in R'' |- || 00:05 || In this tutorial, we will learn: Need for '''functio..."

2020-06-01T13:26:52Z

Created page with "{| border =1 |'''Time''' |'''Narration''' |- || 00:00 || Welcome to this tutorial on '''Functions in R'' |- || 00:05 || In this tutorial, we will learn: Need for '''functio..."

New page

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

|-
|| 00:00
|| Welcome to this tutorial on '''Functions in R''

|-
|| 00:05
|| In this tutorial, we will learn: Need for '''functions'''

|-
|| 00:10
|| How to create a '''user-defined function'''

|-
|| 00:15
|| Scope of '''variables'''

|-
|| 00:17
|| To understand this tutorial, you should know,

|-
|| 00:21
|| Basics of permutation and combination

|-
|| 00:25
|| Basic '''data structures'''

|-
|| 00:28
|| '''Conditional statements'''

|-
|| 00:31
|| If not, please locate the relevant tutorials on '''R''' on this website.

|-
|| 00:38
|| This tutorial is recorded on '''Ubuntu Linux '''OS version 16.04

|-
|| 00:47
|| '''R''' version 3.4.4

|-
|| 00:51
|| '''RStudio''' version 1.1.463

|-
|| 00:56
|| Install '''R''' version 3.2.0 or higher.

|-
|| 01:02
|| For this tutorial, we will use

|-
|| 01:05
|| A '''script''' file '''myFunctions.R'''.

|-
|| 01:10
|| Please download this file from the '''Code files''' link of this tutorial.

|-
|| 01:18
|| I have downloaded and moved this file to '''functions''' folder.

|-
|| 01:24
|| This folder is located in '''myProject''' folder on my '''Desktop'''.

|-
|| 01:31
|| I have also set '''functions''' folder as my '''Working Directory.'''

|-
|| 01:38
|| A '''function''' is a set of '''statements''' organized together to perform a specific task.

|-
|| 01:45
|| '''R''' has a large number of '''built-in functions'''.

|-
|| 01:49
|| In spite of that, sometimes we need to define our own '''functions'''.

|-
|| 01:56
|| '''User-defined functions''' are specific to user’s requirements.

|-
|| 02:02
|| Once created these '''functions''' can be used as the '''built-in functions'''.

|-
|| 02:08
|| An '''R function '''is created by using the '''keyword function'''.

|-
|| 02:14
|| The syntax of an '''R function''' is as follows:

|-
|| 02:20
|| The different parts of a '''function''' are: Name, '''Arguments''', '''Body''', Return value.

|-
|| 02:32
|| Let us switch to '''RStudio'''.

|-
|| 02:35
|| Open the '''script myFunctions.R '''in''' RStudio'''.

|-
|| 02:42
|| Here, we have declared a sample '''vector''' named '''sampleVec'''.

|-
|| 02:48
|| Let us find the '''summary''' of this '''vector''' by using the '''built-in function'''.

|-
|| 02:55
|| In the '''Source''' window, type the following '''command'''.

|-
|| 02:59
|| Save the '''script''' and '''run''' this script by clicking on the '''Source''' button.

|-
|| 03:07
|| The '''summary''' of '''sampleVec''' is displayed.

|-
|| 03:12
|| It includes median, mean, etc.

|-
|| 03:18
|| Similarly, '''R '''has many '''built-in functions''' to make our life easy.

|-
|| 03:24
|| But we can always create a '''function''' of our own, depending on the need.

|-
|| 03:30
|| We will create a '''function''' that computes the '''permutation''' of two numbers.

|-
|| 03:36
|| In the '''Source''' window, type the following '''command'''.

|-
|| 03:42
|| Here, we have named our '''function''' as '''permutation'''.

|-
|| 03:48
|| Next, we have passed two values as '''arguments'''.

|-
|| 03:53
|| Inside the '''function''', the definition of '''permutation''' has been written.

|-
|| 03:58
|| Run the current line by pressing '''Ctrl + Enter''' keys simultaneously.

|-
|| 04:05
|| Now, let us test this '''function''' to check whether it gives correct results.

|-
|| 04:11
|| First, we will calculate the '''permutation''' of 5 and 2.

|-
|| 04:17
|| In the '''Source''' window, type '''permutation''' and in parentheses 5 comma 2.

|-
|| 04:27
|| '''Run''' the current line.

|-
|| 04:29
|| The required value of 20 is displayed.

|-
|| 04:34
|| Thus, our '''function''' has given the correct result.

|-
|| 04:39
|| While creating '''functions''', the '''arguments''' are optional.

|-
|| 04:44
|| Let us create a '''function''' that does not take any '''arguments'''.

|-
|| 04:49
|| We will create a '''function''' named as '''votingEligibility'''.

|-
|| 04:54
|| In the '''Source''' window, type the following '''commands'''.

|-
|| 04:59
|| This '''function''' should print a message whether an Indian citizen is eligible to vote or not.

|-
|| 05:08
|| Remember the minimum age for Indian citizens to vote is 18 years.

|-
|| 05:15
|| Here, we have not passed any '''arguments'''.

|-
|| 05:20
|| '''readline function''' reads a line from the '''terminal''' in interactive use.

|-
|| 05:27
|| '''Run''' this block of code to execute the '''function votingEligibility'''.

|-
|| 05:33
|| Now, we will run this '''function''' to see whether it works.

|-
|| 05:38
|| In the '''Source''' window, type the following '''command'''.

|-
|| 05:42
|| Please note that we are not passing any '''arguments''' inside this '''function'''.

|-
|| 05:49
|| '''Run''' the current line.

|-
|| 05:52
|| We are asked to enter our age.

|-
|| 05:56
|| Let us type 21 and press '''Enter'''.

|-
|| 06:02
|| We get a message, '''You can cast your vote'''.

|-
|| 06:08
|| Now let us say we want to create a '''function''' '''sum_between_two''' such that

|-
|| 06:17
|| it takes two natural numbers '''num1''' and '''num2''' as its '''arguments'''.

|-
|| 06:26
|| Then, it returns the sum of all numbers from '''num1''' to '''num2'''.

|-
|| 06:32
|| For example, if we pass 2 and 6 to the '''function sum_between_two''',

|-
|| 06:42
|| it should return the value of 2 + 3 + 4 + 5 + 6.

|-
|| 06:50
|| Let us switch back to '''RStudio'''.

|-
|| 06:54
|| In the '''Source''' window, type the following '''command'''.

|-
|| 06:59
|| We have named our '''function''' as '''sum_between_two.'''

|-
|| 07:08
|| Also, we have specified the two '''arguments num1 '''and '''num2. '''

|-
|| 07:14
|| Inside the '''function''', we have initialized an object named '''result''' to store the sum.

|-
|| 07:22
|| We have created a '''for loop''' which will increment the '''result '''at each iteration.

|-
|| 07:31
|| '''Run''' this block of code to execute the '''function'''.

|-
|| 07:36
|| Now we test our '''function sum_between_two '''by running it with two '''arguments'''.

|-
|| 07:45
|| In the '''Source''' window, type the following '''command'''.

|-
|| 07:51
|| '''Run''' the current line.

|-
|| 07:53
|| The '''function''' with '''arguments''' 2 and 6 was executed, but we got nothing as output.

|-
|| 08:03
|| Let us investigate what went wrong.

|-
|| 08:07
|| We know that our '''function''' got executed as we did not get any error after executing this line.

|-
|| 08:16
|| It means that the object named '''result ''' got incremented.

|-
|| 08:22
|| Now, we will check the value of the '''result'''.

|-
|| 08:26
|| In the '''Source''' window, type the following '''command'''.

|-
|| 08:31
|| '''Run''' the current line.

|-
|| 08:34
|| It shows, '''Error in print(result) : object 'result' not found.'''

|-
|| 08:40
|| To understand what went wrong, we need to learn a concept named as '''Scope'''.

|-
|| 08:48
|| '''Scope '''is the term used to describe how objects and '''variables''' get defined within '''R'''.

|-
|| 08:56
|| If a '''variable''' is defined inside a '''function,''' then it can be accessed inside the '''function''' only.

|-
|| 09:04
|| So, if we try to access the same '''variable''' outside the '''function''', it will throw an error.

|-
|| 09:12
|| Let us switch to '''RStudio'''.

|-
|| 09:17
|| Here, the '''variable result''' is defined inside the '''function.'''

|-
|| 09:22
|| So its scope is limited to this '''function''' only.

|-
|| 09:27
|| Hence, when we tried to access this '''variable''' outside the '''function''', it threw an error.

|-
|| 09:34
|| For this problem, we can use '''return function'''.

|-
|| 09:39
|| Let us get back to our '''function sum_between_two'''.

|-
|| 09:47
|| Press '''Enter''' at the end of '''for loop'''.

|-
|| 09:53
|| Now type the following '''command'''.

|-
|| 09:56
|| I will resize the '''Console''' window.

|-
|| 10:01
|| Select all lines of the '''function sum_between_two.'''.

|-
|| 10:08
|| Now press '''Ctrl + Enter''' keys together to run the updated '''function'''.

|-
|| 10:17
|| Let us run the '''function''' again with '''arguments''' 2 and 6.

|-
|| 10:23
|| For this, we will run this line.

|-
|| 10:27
|| We see the output 20 as expected.

|-
|| 10:32
|| Let us summarize what we have learnt.

|-
||10:36
|| In this tutorial, we have learnt: Need for '''functions'''

|-
|| 10:41
|| How to create a '''user-defined function'''

|-
|| 10:45
|| Scope of '''variables'''

|-
|| 10:48
|| We now suggest an assignment.

|-
|| 10:51
|| Create a '''function''' which computes combination of the two numbers.

|-
|| 10:57
|| Create a '''function''' which takes a natural number as an '''argument''', and prints '''Fibonacci
'''series

|-
|| 11:05
|| For example, consider '''fibonacci(5). '''It should print the first 5 elements of '''Fibonacci '''series,
i.e. 1, 1, 2, 3, 5.

|-
|| 11:19
|| The video at the following link summarises the Spoken Tutorial project.

|-
|| 11:24
|| Please download and watch it.

|-
|| 11:27
|| We conduct workshops using Spoken Tutorials and give certificates.

|-
|| 11:33
|| Please contact us.

|-
|| 11:36
|| Please post your timed queries in this forum.

|-
|| 11:41
|| Please post your general queries in this forum.

|-
|| 11:44
|| The '''FOSSEE '''team coordinates the '''TBC '''project.

|-
|| 11:48
|| For more details, please visit these sites.

|-
|| 11:52
|| The Spoken Tutorial project is funded by NMEICT, MHRD, Govt. of India

|-
|| 11:59
|| The script for this tutorial was contributed by Varshit Dubey (College of Engineering Pune).

|-
|| 12:07
|| This is Sudhakar Kumar from IIT Bombay signing off.

|-
|| 12:12
|| Thanks for watching.

|-
|}

@@ Line 414: / Line 414: @@
 || 10:08
 || Now press '''Ctrl + Enter''' keys together to run the updated '''function'''.
 |-

@@ Line 5: / Line 5: @@
 |-
 || 00:00
-|| Welcome to this tutorial on '''Functions in R''
+|| Welcome to this tutorial on '''Functions in R'''
 |-
@@ Line 463: / Line 463: @@
 || 11:19
 || The video at the following link summarises the Spoken Tutorial project.
 |-

@@ Line 362: / Line 362: @@
 || 08:48
 || '''Scope '''is the term used to describe how objects and '''variables''' get defined within '''R'''.
 |-
@@ Line 455: / Line 454: @@
 |-
 || 10:57
-|| Create a '''function''' which takes a natural number as an '''argument''', and prints '''Fibonacci
+|| Create a '''function''' which takes a natural number as an '''argument''', and prints '''Fibonacci    '''series
     '''series
 |-
 || 11:05
-|| For example, consider '''fibonacci(5). '''It should print the first 5 elements of '''Fibonacci '''series,
+|| For example, consider '''fibonacci(5). '''It should print the first 5 elements of '''Fibonacci '''series, i.e. 1, 1, 2, 3, 5.
-   i.e. 1, 1, 2, 3, 5.
 |-

@@ Line 258: / Line 258: @@
 || 05:56
 || Let us type 21 and press '''Enter'''.
 |-
@@ Line 311: / Line 310: @@
 ||  07:31
 || '''Run''' this block of code to execute the '''function'''.
 |-

R/C2/Functions-in-R/English-timed - Revision history

Sakinashaikh at 13:31, 1 June 2020

Sakinashaikh at 13:30, 1 June 2020

Sakinashaikh at 13:30, 1 June 2020

Sakinashaikh at 13:28, 1 June 2020

Sakinashaikh: Created page with "{| border =1 |'''Time''' |'''Narration''' |- || 00:00 || Welcome to this tutorial on '''Functions in R'' |- || 00:05 || In this tutorial, we will learn: Need for '''functio..."