Other useful free tools and services

CH-13

Topics

• Data Compression
• Archive Manager
• The VLC Media Player
• Google Maps
• Character Map
• The R Software
• Rational Plan
• Skype

Data Compression

• A Modern computer system has lakhs of files on them.
• It becomes time consuming when we need to transfer a large number of files from one computer to another computer’s storage device.
• If data is to be transferred via Internet then high speed connection and unlimited Internet plan is needed.
• There is a need to reduce the amount of storage space occupied by the files.
• It is also desirable to have a single file to handle rather than a large bunch of files or a complex directory structure.

Data Compression

• Computer scientists have developed techniques to place a whole directory structure into a single file for convenience.
• Such a file is called an “archive”.
• They have also developed a number of techniques for reducing the storage requirements of computer files and directory structures.
• These techniques are called data compression.
• Data compression generally works by identifying repetition in the data and encoding the data in a way that reduces or eliminates such repetition.

Compression techinque example

• Consider the children’s rhyme as below.
• One little, two little, three little, Indians.�Four little, five little, six little Indians�Seven little, eight little, nine little Indians�Ten little Indians boys.
• There are lots of repetition of words.
• We shall have a table that tells us which digit/letter represents which word as below.
• ==========================
• 0:One , 1:little, 2:two , 3:three , 4:four, 5:five A:Indians
• 0 1 2 1 3 1 A
• 4 1 5 1 6 1 A

Compression techinques

• We can replace the digits in place of whole word at the time of storing data.
• Ultimately it reduces the amount of space occupied by the file.
• Afterwards we can replace the digits with the original words and complete the rhyme at the time of reading.
• The technique applied here is very simple.
• Actual data compression programs use far more sophisticated algorithms based on information theory to achieve even greater reduction in size.

Archive Manager

• Linux provides ready-made free and open source software known as Archive Manager for managing archive files.

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Archive Manager

• Archive manager can also be used to explore the contents of archives, to extract files from the archives.
• It allows to add new files to archives.
• The most common compressed file formats are Zip file format and tar.gz file format.
• It allows to combine files or an entire directory tree into a single file known as an archive.
• On Linux systems, tar(tap archiver) is the most common archive format.
• It also provides the facility of compressing the archive to reduce its file size.
• It supports multiple compression algorithms and compressed file format.

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Archive Manager

• The most common compressed file formats are the zip file format and the tar.gz file format.
• The zip file format supports storing multiple files in a single zip file, on Linux systems the common practice is to combine the files into a single uncompressed file in the tar format and then compress the file in the zip format using gzip program.
• Such a file commonly has the extension tar.gz and is called a tar ball.
• Zip format is also used by different applications under different names, like JAR file in Java.

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The VLC Media Player

• Originally vlc is short form of VideoLAN client.
• It is extremely possible because of its versatility and features.
• VLC was started as an academic project by the music-loving students of a university in Paris.
• It is now a community project available under multiple operating systems and has been downloaded over a billion times.
• There are a variety of ways of converting multimedia information coming from hardware devices into computer data and then converting the computer data back into audio/video streams for playing on the hardware devices.
• This conversion and reverse conversion is performed by a software component called codec.

The VLC Media Player

• Each multimedia data format requires its own codec.
• The advantage of VLC is that it supports all the popular codecs and hence all the popular formats.
• It also supports web cameras, HD monitors, speakers of all types, microphones, headphones etc.
• VLC can be started from Applications 🡪 Sound & video
• Media 🡪 Open file to open a file.
• Media 🡪 Open Directory to open a directory.
• View 🡪 Playlist
• Media 🡪 Save playlist to file like m3u.

Google Maps

• Google map is a free Internet-based services provided by Google.
• Google has, over a period of years, collected extensive map data for the whole earth through various means like satellite imagery, cars with cameras mounted, data purchased from other organizations and data provided by millions of individuals around the world.
• It is heavily used on mobile devices like smartphones and tablets.
• The service can be opened from http://www.google.co.in web site. Or directly can be started by http://maps.google.co.in.
• From mobile it can also be started using mobile app.

Google Maps

• On PC, a rough idea of the user’s location can be obtained from the user’s Internet connection.
• On a mobile phone, the user’s location can be known with very high accuracy if the GPS(Global positioning System) facility is used.
• It finds user’s location with an estimated error of only few meters using satellite signals.
• The default view is map view in google map.
• It also guides us from place A to place B with on-screen as well as voice instructions.

Character map

• The character map can be used to enter unicode characters into an application.

Character map

• We can select any script from the left pane.

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• Double click the character to insert it into the text.

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• “Text to copy” shows the inserted characters.

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• We can copy the text given in “Text to copy” and paste it any where in the application where we want.

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• When we want to add few ASCII characters occasionally then character map is a good solution for that.

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The R software

• R is a free environment for statistical computing.
• It is a GNU project.
• It has its own scripting language.
• It is case-sensitive language.
• R has 2 environments namely: command line and Graphical.
• To use R software in graphical environment we need to install graphical editors like R commander or Rstudio from Ubuntu centre.
• When you start R software you will get a welcome message along with the R prompt.
• R prompt allows to enter commands.

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The R software

• R uses # as the comment marker just like the linux shell.
• a <- 10 creates a variable.
• a Shows the value of variable a.
• b <- 20
• a * b multiplies a with b.
• A List can be created using c function.
• L1 <- c(1,2,3,4,5)
• ls() displays list of all variables that we have defined.

Plotting in R

Rational Plan

• People working in different areas like construction, engineering, services and consulting, business or sofware development usually work on a project that is having constratints of time, resource and budget.
• Any delay in completion of the project increases the cost of the project.
• At some point of time to manage this kind of project we need to prepare, maintain and folow a well defined plan.
• Such a plan helps us to complete the project as scheduled, on time and within budget.
• Rationalplan is one such open source software designed to assist project managers throughout the life cycle of their projects.
• It comprises 3 different desktop products: Rationalplan single, multi and viewer.

Rational Plan

• Rationalplan single allows us to manage independent projects that do not have common resources and has no interrelations between different projects.
• Rationalplan multi allows us to manage projects that share company resources across projects.
• It also manages interdependencies between projects.
• Rationalplan viewer is an additional tool developed to share the project in its original file format(.xrp).
• It can be used as well to open microsoft project files.
• Though as of today the support of RationalPlan on Ubuntu 10.04 has been removed it is available for Ubuntu 12.04 and later versions.

Skype

• Skype is a messaging service like yahoo massenger, google talk or Rediff Bol.
• Skype also allows us to make calls over the Internet using our computer.
• It also provides additional features like file transfer and videoconferencing.
• Skype can be downloaded free of cost, though its source code is proprietary and not available for modification.
• To start Skype, choose Applications 🡪 Internet 🡪 Skype.