Difference between revisions of "Scilab/C4/File-handling/English"

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# Basic knowledge of '''Scilab'''.
 
# Basic knowledge of '''Scilab'''.
 
# If not, for relevant spoken tutorials please visit '''spoken hyphen tutorial dot org'''
 
# If not, for relevant spoken tutorials please visit '''spoken hyphen tutorial dot org'''
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* writing to a file using write function,
 
* writing to a file using write function,
 
* reading from a file using read function,  
 
* reading from a file using read function,  
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* open an existing file  using mopen function and  
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* opening an existing file  using mopen function and  
 
* closing an already opened file using mclose function.
 
* closing an already opened file using mclose function.
  
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'''-->random underscore matrix is equal to rand in the bracket 20 comma 1 close the bracket semicolon and press enter'''
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'''-->random underscore matrix is equal to rand in to bracket 20 comma 1 close the bracket semicolon and press enter'''
  
  
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Type'''new underscore vector is equal to read into bracket  in to  quote random dash numbers Dot txt close the quote comma 20 comma 1 close the  bracket and press enter.'''
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Type'''new underscore vector is equal to read into bracket  in to  quote random dash numbers Dot txt close the quotes comma 20 comma 1 close the  bracket and press enter.'''
  
  
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|-
 
|-
 
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide
 
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide
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| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| '''mclose''':  
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| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| '''mclose(fd)''':  
  
 
'''mclose''' command closes the opened file by using '''mopen.'''
 
'''mclose''' command closes the opened file by using '''mopen.'''
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If '''fd''' is omitted <tt>mclose</tt> closes the last opened file.  
 
If '''fd''' is omitted <tt>mclose</tt> closes the last opened file.  
  
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| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Scilab Console
 
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-->mclose(fd_r)
 
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ans =
 
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0.
 
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| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| '''mclose into bracket fd'''closes the opened file by using mopen
 
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Where fd is the file descriptor of the opened file.
 
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If fd is omitted mclose closes the last opened file.
 
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Thats all we have in this tutorial.
 
  
 
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Latest revision as of 12:12, 17 April 2013

Title of script: File Handling in Scilab

Author: Anuradha Amrutkar

Keywords: File Handling, writefile, read file, open file, close file


Visual Cue Narration
Slide Welcome to this spoken tutorial on File Handling using Scilab.
Slide In this tutorial, we will learn
  • File Handling with the following functions;
    • Write Function
    • Read Function
    • mopen
    • mclose
Slide System Requirements

For Demonstration i am using Ubuntu Linux12.04 operating system with Scilab version 5.3.3 installed


Slide Pre-requisites:

You should have

  1. Basic knowledge of Scilab.
  2. If not, for relevant spoken tutorials please visit spoken hyphen tutorial dot org


Slide Now we will see some functions in scilab which are useful for File Handling.

File Handling involves-

  • writing to a file using write function,
  • reading from a file using read function,
  • opening an existing file using mopen function and
  • closing an already opened file using mclose function.


Let us start with writing data to a file.

For this purpose the write() command is used.

Scilab Console


--> random_matrix = rand(20,1)


random_matrix =


0.2113249

0.7560439

0.0002211

0.3303271

0.6653811

0.6283918

0.8497452

0.6857310

0.8782165

0.0683740

0.5608486

0.6623569

0.7263507

0.1985144

0.5442573

0.2320748

0.2312237

0.2164633

0.8833888

0.6525135

Switch to the scilab console window. To begin with let us create a matrix of random numbers. Type;


-->random underscore matrix is equal to rand in to bracket 20 comma 1 close the bracket semicolon and press enter



Scilab Console


--> pwd


Now check the present working directory. Type


-->pwd

ans =


/home/fossee


In my case the present working directory is slash home slash fossee

Make sure that you are in a directory where you have read & write permission , before you execute these commands.

--> write('random-numbers.txt', random_matrix) Now we will write the content of variable random underscore matrix into a text file using the write command. 


Type;--> write into bracket into quotes random dash numbers dot txt close  the  quotes comma random underscore matrix close the bracket and press enter
Let us see whether this file has been created.

I will minimize the scilab console window.


And open the file which will be created and saved in the fossee directory of my computer.

You can see the data from variable random underscore matrix is written in a text file random dash numbers dot txt
Scilab Console


-->new_vector = read('random-numbers.txt', 20, 1)


new_vector =

0.2113249

0.7560439

0.0002211

0.3303271

0.6653811

0.6283918

0.8497452

0.6857310

0.8782165

0.0683740

0.5608486

0.6623569

0.7263507

0.1985144

0.5442573

0.2320748

0.2312237

0.2164633

0.8833888

0.6525135

I will close this file. Coming back to the scilab console. Now we will see how to read the data from a file.


For this we will use the command read as follows,


Typenew underscore vector is equal to read into bracket in to quote random dash numbers Dot txt close the quotes comma 20 comma 1 close the bracket and press enter.


The read command reads all the data from the file mentioned in the argument,


In this case random dash numbers dot txt,


And stores in the variable new underscore vector Press Enter to continue the display

Narration:

-->new_vector = read('random-numbers.txt', 19, 1)

If we modify the above command as


new underscore vector is equal to read into bracket into quote random dash numbers Dot txt comma 19 comma 1


The read command reads only 19 data values from the file mentioned in this argument.


In this case random dash numbers dot txt


And stores in the variable new underscore vector.


Issue this command on the scilab console and verify the output.

Slide Now let us see about themopen function:


fd = mopen(file-name, mode)


mopen command is used to open an existing file in a way compatible to C fopen procedure.


mode is a character string that controls whether the file is opened for

r = Opens the file for reading.

rb = Opens a binary file for reading.

rt = Opens a text file for reading.

w = Creates a new file for writing, or opens and truncates a file to zero length.

wb = Creates a new binary file for writing, or opens and truncates a file to zero length.

wt = Creates a text binary file for writing, or opens and truncates a file to zero length.

a or ab = Appends (opens a file for writing at the end of the file, or creates a file for writing).

r+ or r+b = Opens a file for update (reading and writing)

Scilab Console 
-->fd_r = mopen('random-numbers.txt','rt')
 fd_r  =

    1.
For eg 
fd underscore r is equal to mopen('random-numbers,'rt')

the above command opens the 'random-numbers' as a text and read-only mode.

Slide mclose(fd):

mclose command closes the opened file by using mopen.

mclose(fd)


where fd is the file descriptor of the opened file


If fd is omitted mclose closes the last opened file.


Summary That's all we have in this tutorial. 
You have learnt -
  • File Handling with the following functions:

Write Function

Read Function

mopen

mclose

Slide Watch the video available at the link shown below

It summarises the Spoken Tutorial project

If you do not have good bandwidth, you can

download and watch it

Spoken Tutorial Workshops The Spoken Tutorial Project Team

Conducts workshops using spoken tutorials

Gives certificates to those who pass an online

test

For more details, please write to

contact@spoken-tutorial.org

Acknowledgement Spoken Tutorial Project is a part of the Talk to a

Teacher project

It is supported by the National Mission on

Education through ICT, MHRD, Government

of India

More information on this Mission is available

at: http://spoken-tutorial.org\NMEICT-Intro

This is Anuradha Amrutkar from IIT Bombay

Thank You for joining

Contributors and Content Editors

Lavitha Pereira, Sneha

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