Difference between revisions of "Python-3.4.3/C2/Saving-plots/English"

“Saving Plots”

Objectives

1. Save plots using savefig() function.
2. Save plots in different formats.

System Requirements

• Ubuntu Linux 14.04 operating system
• Python 3.4.3
• IPython 5.1.0

Pre-requisites

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

ipython3

Now, type ipython3 and press Enter.

%pylab and press Enter.

Type percentage pylab and press Enter

'Creating a basic plot'

x = linspace(-3*pi, 3*pi, 100)

To do this, type,

x equals to linspace(minus 3 star pi comma 3 star pi comma 100) in the console.

Let us plot a sine curve for the points stored in variable x

plot(x, sin(x))

Don't close the plot window for rest of the tutorial.

Now let us see how to save the plot.

savefig()

Syntax: savefig(fname)

savefig function takes one argument which is the filename.

savefig('sine.png')

This saves the file in present working directory.

The characters after the dot in the filename is the extension.

It determines the format in which you want to save.

Type pwd and press Enter

Type pwd in the console and press Enter

Highlight the /home/fossee/ using mouse cursor

Type savefig('slash home slash fossee slash sine.png')

Path for windows System

'C:\\Users\\fossee\\Desktop\\sine.png'

For Windows, give the entire file path as shown here.

Here fossee is the username in Windows and sine.png file is to be saved on Desktop.

Highlight the .png part using mouse movements

This will ensure that the image is saved as a PNG file.

Now let us locate the file sine.png which we had saved earlier.

Open the browser, navigate to /home/fossee

and highlight the file sine.png

(slash)home(slash)fossee,

Let us navigate to (slash)home(slash)fossee using the file browser.

Open the file sine.png and

show it for two-three seconds and then close it.

More on savefig()

pdf - portable document format,

ps - post script,

eps - encapsulated post script, to be used with LaTeX documents

svg - scalable vector graphics,

png - portable network graphics

Exercise 1

Save the sine plot in the eps format.

Let us see the output for this exercise.

savefig('/home/fossee/sine.eps')

and press Enter.

Highlight the file sine.eps for 2 seconds and

then double click and open the file.

<pause>

We see the file sine.eps here.

Exercise 2

Save the sine plot in PDF, PS and SVG formats.

Summary slide

1. Save plots using the savefig() function.
2. Save the plots in different formats like
   • pdf - ps - png - svg - eps

Assignment

1. Which command is used to save a plot?
   • saveplot()
   • savefig()
   • savefigure()
   • saveplt()
2. savefig('sine.png')saves the plot in
   • The root directory 'slash' (on GNU/Linux, Unix based systems), 'C:' (on windows)
   • Will result in an error as full path is not supplied.
   • The current working directory.
   • Predefined directory like “slash documents.”

Solutions

1. To save a plot, we use the savefig() function.
2. If we save a file without complete path, it gets saved in the current working directory.

Forum

Fossee Forum

Textbook Companion

Acknowledgment

http://spoken-tutorial.org

For more details, visit this website.

Thank you.