R/C2/Plotting-Bar-Charts-and-Scatter-Plot/English - Revision history

Madhurig at 17:57, 1 June 2019

2019-06-01T17:57:46Z

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Nancyvarkey at 02:48, 31 May 2019

2019-05-31T02:48:16Z

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Sudhakarst at 12:03, 27 May 2019

2019-05-27T12:03:57Z

Sudhakarst at 12:03, 27 May 2019

2019-05-27T12:03:13Z

Sudhakarst at 12:02, 27 May 2019

2019-05-27T12:02:44Z

Sudhakarst at 12:01, 27 May 2019

2019-05-27T12:01:53Z

Sudhakarst: Created page with "'''Title of the script''': Plotting Bar Charts and Scatter Plots '''Author''': Tushar Bajaj (TISS Mumbai) and Sudhakar Kumar (IIT Bombay) '''Keywords''': R, RStudio, graphs..."

2019-05-27T12:01:34Z

Created page with "'''Title of the script''': Plotting Bar Charts and Scatter Plots '''Author''': Tushar Bajaj (TISS Mumbai) and Sudhakar Kumar (IIT Bombay) '''Keywords''': R, RStudio, graphs..."

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'''Title of the script''': Plotting Bar Charts and Scatter Plots

'''Author''': Tushar Bajaj (TISS Mumbai) and Sudhakar Kumar (IIT Bombay)

'''Keywords''': R, RStudio, graphs, bar chart, labels, scatter plot, correlation, video tutorial, spoken tutorial

{| border =1
|'''Visual Cue’’’
|'''Narration’’’
|-
|| Show slide

Opening slide
|| Welcome to this tutorial on '''Plotting bar charts and scatter plot'''.
|-
|| Show slide

Learning Objectives

|| In this tutorial, we will learn how to:
* Plot '''bar charts'''
* Plot '''scatter plot'''
* Find the correlation coefficient between two objects

|-
|| Show slide

Pre-requisites

https://spoken-tutorial.org

|| To understand this tutorial, you should know,
* '''Data frames''' in '''R'''
* Basics of Statistics

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

System Specifications
|| This tutorial is recorded on* '''Ubuntu Linux '''OS version '''16.04'''
* '''R''' version '''3.4.4'''
* '''RStudio''' version '''1.1.463'''

Install '''R''' version '''3.2.0''' or higher.
|-
|| Show slide

Download Files
|| For this tutorial, we will use
* A data frame '''moviesData.csv'''
* A script file '''barPlots.R'''.

Please download these files from the '''Code files''' link of this tutorial.
|-
|| [Computer screen]

Highlight '''moviesData.csv '''and''' barPlots.R '''in the folder '''Plots '''
|| I have downloaded and moved these files to '''Plots''' folder.

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

I have also set '''Plots''' folder as my '''Working Directory.'''
|-
||
|| Let us switch to '''Rstudio'''.
|-
|| Highlight '''barPlots.R''' in the '''Files '''window''' '''of '''RStudio '''
|| Open the '''script barPlots.R '''in''' RStudio'''.
|-
|| Highlight the '''Source''' button
|| Run this '''script''' by clicking on '''Source''' button.
|-
|| Highlight '''movies''' in the '''Source''' window
|| '''movies''' '''data frame''' opens in the '''Source''' window.
|-
|| Highlight '''dim(movies)''' in the '''Console''' window
|| It has 600 observations of 31 variables.
|-
|| Highlight the scroll bar in the '''Source''' window
|| In the '''Source''' window, scroll from left to right. This will enable us to see the remaining objects of '''movies''' '''data frame'''.
|-
|| Highlight '''imdb_rating''' in the '''Source''' window
|| Now, we will learn how to draw a bar chart of the object named '''imdb '''underscore '''rating''' in '''movies'''.
|-
|| Show slide

Bar Chart
|| * A '''bar chart '''represents data in rectangular bars with length of the bar proportional to the value of the variable.
* R uses the function '''barplot''' to create bar charts.

|-
||
|| Let us switch to '''RStudio'''.
|-
|| Highlight '''movies''' in the '''Source''' window
|| For the sake of simplicity, we are considering only the first 20 observations of '''movies''' to draw a '''bar chart'''.
|-
|| Highlight '''barPlots.R '''in the '''Source''' window
|| Click on the '''script''' '''barPlots.R'''
|-
|| ''' '''

'''[Rstudio]'''

'''moviesSub <- movies[1:20,]'''
|| In the '''Source''' window, type the following command.

Save the '''script''' and run the current line by pressing '''Ctrl + Enter '''keys simultaneously.
|-
||
|| Let me resize the '''Source''' window.
|-
|| Highlight '''moviesSub''' in the '''Environment''' window
|| '''moviesSub''' with 20 observations is loaded in the '''Environment'''.

Now, we draw a bar chart of '''imdb_rating''' for these movies.
|-
|| [RStudio]

'''barplot(moviesSub$imdb_rating,'''

'''ylab="IMDB Rating",'''

'''xlab = "Movies", '''

'''col="blue",'''

'''ylim=c(0,10),'''

'''main="Movies' IMDB Rating")'''
|| In the '''Source''' window, type the following command.
|-
|| Highlight '''barplot''' in the '''Source''' window
|| Here, we have used the following arguments:
* '''moviesSub dollar sign imdb '''underscore''' rating '''is the data for plotting
* '''ylab''' and '''xlab''' for adding labels to the respective axes
* '''col''' to set the color of bins
* '''ylim''' to set the range of values on Y-axis
* '''main''' for adding a title to the bar chart

|-
|| Highlight '''Run''' button in the '''Source''' window
|| Run the current line.
|-
|| Highlight the plot in the '''Plots''' window
|| The bar chart is displayed with '''Movies''' on X-axis and their '''imdb_rating '''on Y-axis.
|-
|| Highlight '''Files''' and '''Plots''' window
|| In the '''Plots''' window, click on '''Zoom''' to maximize the plot.
|-
|| Highlight the first bar in the plot
|| This particular movie has an '''IMDB rating''' of approximately 6.
|-
|| Highlight the third bar in the plot
|| Similarly, this particular movie has an '''IMDB rating''' of approximately 8.

However, we do not know the name of the movies.
|-
||
|| So, we will add more arguments in '''barplot '''function to show the names of movies on X-axis.
|-
||
|| Close this plot.
|-
|| [RStudio]

'''barplot(moviesSub$imdb_rating,'''

'''ylab="IMDB Rating",'''

'''col="blue",'''

'''ylim=c(0,10),'''

'''main="Movies' IMDB Rating",'''

'''names.arg=moviesSub$title)'''
|| In the '''Source''' window, type the following command.
|-
|| Highlight '''names.arg''' in the '''Source''' window
|| Here, we have used the argument '''names.arg''' and set it to '''title'''.

Remember, '''title''' column in '''moviesSub''' contains the names of movies.
|-
|| Highlight '''Run''' button in the '''Source''' window
|| Run the current line.
|-
|| Highlight '''Files''' and '''Plots''' window
|| In the '''Plots''' window, click on '''Zoom''' to maximize the plot.
|-
|| Highlight X-axis of the plot
|| Now, the names of movies are displayed on the X-axis.

But not for all movies.

This is due to the point that the names are too long to be accommodated.

That’s why, we will make these names perpendicular to X-axis.
|-
||
|| Close this plot.
|-
|| [RStudio]

'''barplot(moviesSub$imdb_rating,'''

'''ylab="IMDB Rating",'''

'''col="blue",'''

'''ylim=c(0,10),'''

'''main="Movies' IMDB Rating",'''

'''names.arg=moviesSub$title, '''

'''las = 2)'''
|| In the '''Source''' window, type the following command.
|-
||

Highlight '''las''' in the '''Source''' window
|| Here, we have used '''las''' argument.

'''las '''equal to''' 2''' produces labels which are at right angles to the axis.
|-
|| Highlight '''Run''' button in the '''Source''' window
|| Run the current line.
|-
|| Highlight '''Files''' and '''Plots''' window
|| In the '''Plots''' window, click on '''Zoom''' to maximize the plot.
|-
|| Highlight the plot in the '''Plots''' window
|| Now the names for all the movies are displayed on X-axis.

For example, '''Filly Brown''' has an '''IMDB rating''' of approximately 6.
|-
|| Highlight the plot in the '''Plots''' window
|| However, longer names are being truncated.

We can add more arguments to '''barplot''' function for adjusting labels.

For more information, please refer to the '''Additional Material''' section on this website.
|-
||
|| Close this plot.
|-
|| Highlight '''movies''' in the '''Source''' window
|| In the '''Source''' window, click on '''movies. '''
|-
|| Highlight '''imdb_rating''' and '''audience_score '''in the '''Source''' window
|| Let us analyze the relation between '''imdb '''underscore''' rating''' and '''audience '''underscore '''score. '''

For this, we will draw a '''scatter plot''' with these two objects by using '''plot''' function.

Remember, we have already learnt how to plot a single object.
|-
|| Show Slide

Scatter Plot
|| * '''Scatter plot''' is a graph in which the values of two variables are plotted along two axes.
* The pattern of the resulting points reveals the correlation.

|-
||
|| Let us switch to '''RStudio'''.
|-
|| Highlight '''barPlots.R '''in the '''Source''' window
|| In the '''Source''' window, click on the '''script''' '''barPlots.R'''
|-
|| [RStudio]

'''plot(x = movies$imdb_rating, '''

'''y = movies$audience_score,'''

'''main = "IMDB Rating vs Audience Score", '''

'''xlab = "IMDB Rating", '''

'''ylab = "Audience Score", '''

'''xlim = c(0,10),'''

'''ylim = c(0,100),'''

'''col = "blue") '''
|| In the '''Source''' window, type the following command.
|-
|| Highlight '''plot''' function in the '''Source''' window
|| Here, we have kept '''imdb '''underscore '''rating''' on the X-axis and '''audience '''underscore '''score '''on the Y-axis.
|-
|| Highlight '''xlim''' in the '''Source''' window
|| As '''imdb '''underscore''' rating''' of any movie varies between 0 and 10, we have set the range of values on X-axis from 0 to 10.
|-
|| Highlight '''ylim''' in the '''Source''' window
|| Similarly, we have set the range of values on Y-axis from 0 to 100.
|-
|| Highlight '''Run''' button in the '''Source''' window
|| Save the script and run the current line.
|-
|| Highlight '''Files''' and '''Plots''' window
|| In the '''Plots''' window, click on '''Zoom''' to maximize the plot.
|-
|| Highlight the plot in the '''Plots''' window
|| We can observe that the movies having higher '''imdb '''underscore '''rating '''has a high '''audience '''underscore '''score'''.
|-
||
|| Close this plot.
|-
||
|| Now we will learn how to calculate the correlation coefficient between '''imdb '''underscore '''rating '''and '''audience '''underscore '''score'''.

For this, we use '''cor''' function.
|-
|| [RStudio]

'''cor(movies$imdb_rating, movies$audience_score)'''
|| In the '''Source''' window, type the following command.
|-
|| Highlight '''Run''' button in the '''Source''' window
|| Save the '''script''' and run the current line.
|-
|| Highlight the output in the '''Console''' window
|| The correlation coefficient between '''imdb '''underscore''' rating '''and '''audience '''underscore '''score''' is evaluated as 0.865.
|-
|| Highlight the output in the '''Console''' window
|| The value of correlation coefficient is always between -1 and +1.

A positive value indicates that the variables are positively related.
|-
||
|| Let us summarize what we have learnt.
|-
|| Show slide

Summary
|| In this tutorial, we have learnt how to:
* Plot '''bar charts'''
* Plot '''scatter plot'''
* Find the correlation coefficient between two objects

|-
|| Show slide

Assignment
|| We now suggest an assignment.
* Read the file '''moviesData.csv'''. Create a bar chart of '''critics '''underscore '''score''' for the first 10 movies.
* Create a '''scatter plot''' of''' imdb '''underscore '''rating''' and '''imdb '''underscore '''num '''underscore '''votes''' to see their relation.
* Save both the plots.

|-
|| Show slide

About the Spoken Tutorial Project
|| The video at the following link summarises the Spoken Tutorial project.

Please download and watch it.
|-
|| Show slide

Spoken Tutorial Workshops
|| We conduct workshops using Spoken Tutorials and give certificates.

Please contact us.
|-
|| Show Slide

Forum to answer questions
|| Please post your timed queries in this forum.
|-
|| Show Slide

Forum to answer questions
|| Please post your general queries in this forum.
|-
|| Show Slide

Textbook Companion
|| The '''FOSSEE '''team coordinates the '''TBC '''project.

For more details, please visit these sites.
|-
|| Show Slide

Acknowledgment
|| The Spoken Tutorial project is funded by '''NMEICT''', '''MHRD''', Govt. of India
|-
|| Show Slide

Thank You
|| The script for this tutorial was contributed by Tushar Bajaj (TISS Mumbai).

This is Sudhakar Kumar from IIT Bombay signing off. Thanks for watching.
|-
|}

@@ Line 261: / Line 261: @@
 Scatter Plot
-|| * '''Scatter plot''' is a graph in which the values of two variables are plotted along two axes.
+||
 * The pattern of the resulting points reveals the correlation.

@@ Line 87: / Line 87: @@
 Bar Chart
-|| * A '''bar chart '''represents data in rectangular bars with length of the bar proportional to the value of the variable.
+||
 * R uses the function '''barplot''' to create bar charts.

@@ Line 17: / Line 17: @@
 Learning Objectives
 || In this tutorial, we will learn how to:
@@ Line 24: / Line 22: @@
 * Plot '''scatter plot'''
 * Find the correlation coefficient between two objects
 |-
@@ Line 109: / Line 106: @@
 '''moviesSub <- movies[1:20,]'''
 || In the '''Source''' window, type the following command.
 Save the '''script''' and run the current line by pressing '''Ctrl + Enter '''keys simultaneously.
@@ Line 143: / Line 139: @@
 * '''ylim''' to set the range of values on Y-axis
 * '''main''' for adding a title to the bar chart
 |-
@@ Line 244: / Line 239: @@
 || Highlight the plot in the '''Plots''' window
 || However, longer names are being truncated.
 We can add more arguments to '''barplot''' function for adjusting labels.
 For more information, please refer to the '''Additional Material''' section on this website.
@@ Line 269: / Line 262: @@
 || * '''Scatter plot''' is a graph in which the values of two variables are plotted along two axes.
 * The pattern of the resulting points reveals the correlation.
 |-
@@ Line 349: / Line 341: @@
 * Plot '''scatter plot'''
 * Find the correlation coefficient between two objects
 |-
@@ Line 359: / Line 350: @@
 * Create a '''scatter plot''' of''' imdb '''underscore '''rating''' and '''imdb '''underscore '''num '''underscore '''votes''' to see their relation.
 * Save both the plots.
 |-
@@ Line 373: / Line 363: @@
 Spoken Tutorial Workshops
 || We conduct workshops using Spoken Tutorials and give certificates.
 Please contact us.
@@ Line 403: / Line 392: @@
 Thank You
 || The script for this tutorial was contributed by Tushar Bajaj (TISS Mumbai).
 This is Sudhakar Kumar from IIT Bombay signing off. Thanks for watching.
 |-
 |}

@@ Line 5: / Line 5: @@
 '''Keywords''': R, RStudio, graphs, bar chart, labels, scatter plot, correlation, video tutorial, spoken tutorial
-{| border =1
+{| border = 1
-|'''Visual Cue’’’
+|'''Visual Cue'''
-|'''Narration’’’
+|'''Narration'''
 |-
 || Show slide