Difference between revisions of "Python-3.4.3/C2/Plotting-Charts/English"

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type '''%pylab '''and press '''Enter.'''
 
type '''%pylab '''and press '''Enter.'''
−
| style="background-color:#ffffff;border:1pt solid #000001;padding-top:0in;padding-bottom:0in;padding-left:0.0125in;padding-right:0.075in;"| Let us initialise the '''pylab''' package.
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| style="background-color:#ffffff;border:1pt solid #000001;padding-top:0in;padding-bottom:0in;padding-left:0.0125in;padding-right:0.075in;"| Let us initialize the '''pylab''' package.
  
 
Type '''%pylab '''and press''' Enter.'''
 
Type '''%pylab '''and press''' Enter.'''
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| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0in;padding-bottom:0in;padding-left:0.0382in;padding-right:0.075in;"| The syntax for pie() function is as follows:
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0in;padding-bottom:0in;padding-left:0.0382in;padding-right:0.075in;"| The syntax for pie() function is as follows:
  
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'''pie inside parentheses values comma labels equal to labels'''
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'''pie ''inside parentheses'' values ''comma'' labels ''equal to'' labels'''
  
 
* where '''values are '''the data to be plotted
 
* where '''values are '''the data to be plotted
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'''year comma profit equal to loadtxt inside parentheses inside single quotes add the path to the file company-a-data.txt comma unpack equal to True'''
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'''year ''comma'' profit ''equal to'' loadtxt ''inside parentheses inside single quotes'' add the path of the file company-a-data.txt ''comma'' unpack ''equal to'' True''' and press '''Enter'''
  
  
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'''unpack = True --> returns''' the '''transposed array '''of '''data'''
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'''unpack ''equal to'' True --> returns''' the '''transposed array '''of '''data'''
  
 
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| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0in;padding-bottom:0in;padding-left:0.0382in;padding-right:0.075in;"| Type '''clf open and close parentheses '''to clear the plot window, if any plots executed previously.
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| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0in;padding-bottom:0in;padding-left:0.0382in;padding-right:0.075in;"| Type '''clf ''open and close parentheses'' '''to clear the plot window, if any plots executed previously.
  
  
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Type '''pie(profit,labels=year)'''
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Type '''pie(profit ''comma'' labels equal to year)''' and press '''Enter'''
  
  

Revision as of 16:45, 8 June 2017

Title of script: Plotting Charts

Author: Trupti Kini, Thirumalesh H S

Keywords: Python, IPython, pylab, scatter plot, charts, matplotlib help


Visual Cue Narration
Show slide


Hello friends. Welcome to the tutorial on plotting charts
Show slide

Learning Objectives


At the end of this tutorial, you will be able to -


  • Create pie charts
  • Create bar charts and
  • Find more information on matplotlib


Show slide

System Specifications

To record this tutorial, I am using
  • Ubuntu Linux 14.04 operating system
  • Python 3.4.3
  • IPython 5.1.0


Show slide

Pre-requisites

To practice this tutorial, you should know how to
  • run basic Python commands on the ipython console
  • Load data from files and
  • Plot data.

If not, see the relevant Python tutorials on this website.

Open [Terminal] and type

ipython3


Let us first open the Terminal by pressing Ctrl+Alt+T keys simultaneously.

Now, type ipython3 and press Enter.

[IPython console]

type %pylab and press Enter.

Let us initialize the pylab package.

Type %pylab and press Enter.

Show Slide

Pie chart


A pie chart is a circular chart divided into sectors, to illustrate numerical proportion
Show Slide

pie() function

Syntax:

pie(values, labels= labels)

  • values – the data to be plotted
  • labels – the label for each wedge in the pie chart


The syntax for pie() function is as follows:

pie inside parentheses values comma labels equal to labels

  • where values are the data to be plotted
  • and labels – the label for each wedge in the pie chart


Show Slide

Exercise 1

  • Plot a pie chart representing the profit percentage of company A.
  • Use the data from file company-a-data.txt available in the code file link of this tutorial



[File browser]

Open the file company-a-data.txt and show the content

The data file has two columns with a set of values in each column.


The first column represents years. The second column represents the profit percentages.

[IPython Terminal]


year, profit = loadtxt('company-a-data.txt', unpack = True)


To produce a scatter plot,


we first need to load the data from the file using loadtxt command. Let us clear the terminal

Type


year comma profit equal to loadtxt inside parentheses inside single quotes add the path of the file company-a-data.txt comma unpack equal to True and press Enter


unpack equal to True --> returns the transposed array of data

[Ipython Terminal]


clf()

pie(profit,labels=year)


Type clf open and close parentheses to clear the plot window, if any plots executed previously.


Type pie(profit comma labels equal to year) and press Enter



[Plot Window]


Show pie chart plot

Notice that we passed two arguments to the function pie().


First one being the values, which is profit in our case.


The next one being the set of labels to be used in the pie chart, which is year in our case.

Show Slide

Exercise 2


Pause the video here, try out the following exercise and resume the video.


Plot a pie chart with the same data with the following colors for each wedges.


  • white, red, black, magenta,
  • yellow, blue, green, cyan,
  • yellow, magenta and blue.

Hint: In your ipython interpreter, try typing pie question mark

[IPython Terminal]


clf()


pie(profit,labels=year,colors=('w','r','k','m','y','b','g','c','y','m','b'))


Solution to Exercise 2


Clear the plot window by typing clf open and close parentheses


Type pie inside parentheses profit comma labels equal to year comma colors equal to inside parentheses color codes


This will display a pie chart with each wedge having the color as specified in the parameters.



Show Slide

Bar chart


A bar chart is a chart
  • with rectangular bars
  • with lengths proportional to the values that they represent.


Show Slide


bar() function

The syntax for bar chart is:

bar(x, y)

  • x – a sequence of data
  • y - a sequence of data, the same length of x


Show Slide

Exercise 3


  • Plot a bar chart representing the profit percentage of company A.
  • Use the data from file company-a-data.txt.


[IPython Terminal]


clf()

bar(year, profit)


Solution to Exercise 3


Clear the plot window by typing clf open and close parentheses


Type bar inside parentheses year comma profit


This will display a bar chart representing the profit percentage of company A

Show Slide

Exercise 4


Plot a bar chart as shown in the image:


Hint: Bar chart is not filled and which is hatched with 45o slanting lines,

The data for the chart may be obtained from the file company-a-data.txt.


Hint: In your ipython interpreter, try typing bar question mark

Clue is to try typing bar? In ipython interpreter.

[Ipython Terminal]

clf()


bar(year,profit,fill=False,hatch='/')


Solution to Exercise 4


Clear the plot window by typing clf()

Type 'bar inside parentheses year comma profit comma fill equal to False comma hatch equal to slanting line


This will display a bar chart which is not filled and which is hatched with 45o slanting lines

Show Slide

"Getting help on matplotlib"

{SHOW WEBSITE while narrating}

Help about matplotlib can be obtained from matplotlib.sourceforge.net/contents.html

More plots can be seen at

matplotlib.sourceforge.net/users/screenshots.html

and also at matplotlib.sourceforge.net/gallery.html



Show Slide

Summary slide


This brings us to the end of this tutorial.


In this tutorial we learnt to,


  • Plot a pie chart using pie() function
  • Plot a bar chart using bar() function
  • Access the matplotlib online help


Show Slide

Assignment


Here are some self assessment questions for you to solve.


1.What statement can be issued to generate a bar chart with vertical line hatching?

  • bar(x, y, color='w', hatch='/')
  • bar(x, y, fill=False, hatch='//')
  • bar(x, y, fill=False, hatch='|')
  • bar(x, y, color='w', hatch='\')


Show Slide

Solution to assignment


And the answers,


  1. bar(x, y, fill=False, hatch='|') is the correct option to generate a bar chart with vertical line hatching.


Show Slide

Forum

Please post your timed queries in this forum.
Show Slide

Fossee Forum

Please post your general queries on Python in this forum.
Show Slide

Textbook Companion

FOSSEE team coordinates the TBC project.
Show Slide

Acknowledgment

http://spoken-tutorial.org

Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India.

For more details, visit this website.

Previous slide This is _________ from IIT Bombay (or FOSSEE, if you wish) signing off.

Thank you.

Contributors and Content Editors

Nancyvarkey, Nirmala Venkat, Trupti

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