R session

R workspace, Object and .RData file

The R program’s structure is similar to the programs written in other computer languages such as C or its successors C++ and Java. However, important differences between these languages and R are (i) R has no header files, (ii) most of the declarations are implicit, (iii) there are no pointers in R, and (iv) text and strings as vectors can be defined and manipulated directly.

R is a functional language. Most of the computation in R is handled using functions. The R language environment is designed to facilitate the development of new scientific computation tools.

R Objects

Everything (such as functions and data structure) in R is an object. To see the names of all objects in the R workspace, on the R command prompt just type,

> ls()

objects() is an alternative to ls() function. Similarly, typing the name of any object on the R prompt displays (prints) the content of that object. As an example type q, mean, and lm, etc. on the R prompt.

R Workspace

It is possible to save individual objects or collections of objects into a named image file. The named image file has an extension of .RData. Some possibilities to save an object from R workspace are:

To save the content of R workspace into a file .RData, type

> save.image()

To save objects in the file archive.RData, type

> save.image(file = "archive.RData")

To save some required objects in data.RData, type

> save(x, y, file = "data.RData")

These image files can be attached to make objects available in the next R session. For example.

> attached ("arvhive.RData")
R workspace

Note that when quitting, R offers the option of saving the workspace image. By default, the workspace is saved in an image file (.RData) in the working directory. The image file can be used in the next R session. Saving the workspace image will save everything from the current workspace. Therefore, use rm() function to remove objects that are not further required in the next R session.

For further details about saving and loading R workspace visit: http://rfaqs.com/saving-and-loading-r-workspace

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R Basic FAQs

Question: How to start (Run) R Language in Windows Operating System?
Answer: In Microsoft Windows, during installation, the R installer will have created a Start menu item and an icon for R on your system’s desktop. Double click R icon from desktop or from the start menu list to Run R program. For Windows 7, 8 or 10, you can use a search term like “R x64 3.2.1” (64-bit version) or “R i386 3.2.1” (32-bit version). R GUI will launch.

Question: How R can be used as a calculator?
Answer: Starting R will open the console where the user can type commands. To use R as calculator one has to enter the arithmetical expression after > prompt. For example

> 5 + 4
> sqrt(37)
> 2*4^2+17*4-3

Question: How to Quit R session?
Answer: In R console on R command prompt just type

> q( )

Question: What is q()?
Answer: The q() is a function that is used to tell R to quit. When q() is entered in R console and press Enter key, you will be asked whether to save an image of the current workspace or not or to cancel. Note that only typing q tells R to show the content of this function. The action of this function is to quit R.

Question: What is workspace in R?
Answer: The workspace in R is an image that contains a record of the computations one have done and it may contain some saved results.

Question: How to record work in R?
Answer: Rather than saving the workspace, one can record all the commands that one have entered in R console. Recording work in R, the R workspace can be reproduced. The easiest way is to enter the commands in R’s script editor available in the File menu of R GUI.

Question: What is R Script Editor?
Answer: R script editor is a place where one can enter commands. Commands can be executed by highlighting them and hitting CTRL+R (mean RUN). At the end of an R session, one can save the final script for a permanent record of one’s work. A text editor such as Notepad can also be used for this purpose.
Note that in R console only one command can be entered at a time because after pressing Enter key the R command executed immediately.

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