Scilab/C4/File-handling/English

Title of script: File Handling in Scilab

Author: Anuradha Amrutkar

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

Visual Clue	Narration
Slide	Welcome to this spoken tutorial on File Handling using Scilab.
Slide	In this tutorial, we will learn File Handling Write Function Read Function mopen Function mclose Function
Slide	Pre-requisites: You should have Basic knowledge of Scilab. If not, for relevant tutorials please visit spoken hyphen tutorial dot org
Slide	System Requirements For Demonstration: Ubuntu Linux12.04 operating system is used with Scilab version 5.3.3 installed
Slide	Now we will see some functions in scilab which are useful for File Handling. File Handling involves- writing to a file, reading from a file, open an existing file and closing the opened file
	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	To begin with let us create a matrix of random numbers. -->random underscore matrix is equal to rand inside bracket 20 comma 1
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. --> write inside bracket open single quotes random dash numbers dot txt close single quotes comma random underscore matrix
	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 home directory of my computer.
	You can see the data from variable random underscore matrix is written to a text file radom 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	Now we will see how to read the data from a file. For this we will use the command read as follows, new underscore vector is equal to read open bracket open single quote random dash numbers Dot txt close single quote comma 20 comma 1 close bracket 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
Narration: -->new_vector = read('random-numbers.txt', 19, 1)	If we modify the above command as new underscore vector is equal to read open bracket open single quote randomdash numbers Dot txt close single quotecomma 19 comma 1 close bracket The read command reads only 19 data values from the file mentioned in the 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	mopen: 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 switching to the scilab console type fd underscore r is equal to mopen('random-numbers.txt','rt') the above command opens the 'random-numbers' as text and read-only mode.
Slide	mclose: 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.
Scilab Console -->mclose(fd_r) ans = 0.	mclose inside bracket fd_r the above command closes the 'random-numbers.txt' file.
Summary	That's all we have in this tutorial. Let us summarize what we learnt - File Handling with the following functions: Write Function Read Function mopen Function mclose Function
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