R Language Basics

The R language is capable of performing from easy to advanced numerical calculations. Although R can compute any computation up to 16 digits accurately, a user may not always want to use (or get) that many digits in his final results or computations. In such cases, one can use a couple of functions to round off numbers in R Language. To round off a number to two or more digits after the decimal point, one can use the round() function as follows:

Rounding Off Numbers in R Language

The round off numbers in R language can be done by using the round() function.

round(123.456,digits = 2)

##
123.46

One can also use the round() function to round off numbers to multiples of 10, 100, and so on. For that purpose, one just needs to add a negative number as the digits argument: For example

round(-123.456,digits = -2)

##
-100

Significant Digits in R Language

If someone needs to specify the number of significant digits to be retained, regardless of the size of the number, you use the signif() function instead:

signif(-123.456,digits = 4)
##
-123.5

signif(-123.456, digits=3)
##
-123

signif(-123.456, digits=2)
##
-120

Both round() and signif() function round off the numbers to the nearest possible number. So, if the first digit that is dropped is smaller than 5, the number is rounded down. If the number is bigger than 5, the number is rounded up. On the other hand, if the first digit that is dropped is exactly 5, R Language uses a rule that is common in programming languages: Always round to the nearest even number. For example, round(1.5) and round(2.5) both return 2. Similarly, for example, round(-4.5) returns -4.

Rounding off Numbers floor(), ceiling(), and trunc() Functions

Contrary to round(), three other functions always round off the numbers in the same direction:

floor(x) rounds to the nearest integer that is smaller than $x$. So, floor(123.45) becomes 123 and floor(-123.45) becomes –124.

ceiling(x) rounds to the nearest integer that’s larger than $x$. This means ceiling(123.45) becomes 124 and ceiling(-123.45) becomes –123.

trunc(x) rounds to the nearest integer in the direction of 0. So, trunc(123.65) becomes 123 and trunc(-123.65) becomes –123.

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The post is about R Language Basics and R Language Frequently Asked Questions. The contents are in the form of questions and answers. Let us start with R Language Basics Questions and Answers.

R Basics

Question: How to start (Run) R Language in the 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 the R icon from the desktop or the start menu list to Run the 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.

Using R as a Calculator

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

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

R Workspace

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

Question: How to record works[ace in R?
Answer: Rather than saving the workspace, one can record all the commands that one has entered in the 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.

R Script Editor

Question: What is R Script Editor?
Answer: The 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 the R console, only one command can be entered at a time because after pressing the Enter key the R command executed immediately.

Quitting R Session

Question: How to quit the R session?
Answer: In the R console on the 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 the R console and press the 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.

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Launching R Console in Windows

In this article, we will learn how to use R as a Calculator. Before using R as a calculator, one needs to launch the R software first. In the Windows Operating system, The R installer will have created an icon for R on the desktop and a Start Menu item. Double-click the R icon to start the R Program; R will open the console, to type R commands.

R Prompt

The greater than sing (>) in the console is the prompt symbol. In this tutorial, we will use the R language as a calculator (we will be Using R for the computation of mathematical expressions), by typing some simple mathematical expressions at the prompt (>). Anything that can be computed on a pocket calculator can also be computed at the R prompt. After entering the expression on the prompt, you have to press the Enter key from the keyboard to execute the command.

Using R as a Calculator

Some examples using R as a calculator are as follows

1 + 2   #add two or more numbers
1 - 2   #Substracts two or more numbers
1 * 2   #multiply two or more numbers
1 / 2   #divides two more more numbers
1 %/% 2 #gives the integer part of the quotient
2 ^ 1   #gives exponentiation
31 %% 7 #gives the remainder after division

These operators also work fine for complex numbers.

Upon pressing the enter key, the result of the expression will appear, prefixed by a number in a square bracket:

1 + 2

# output
[1] 54

The [1] indicates that this is the first result from the command.

Scientific Calculator Type Functions in R

One can also use R as an advanced scientific calculator. Some advanced calculations that are available in scientific calculators can also be easily done in R for example,

sqrt(5)      #Square Root of a number
log(10)      #Natural log of a number
sin(45)      #Trignometric function (sin function)
pi           #pi value 3.141593
exp(2)       #Antilog, e raised to a power
log10(5)     #Log of a number base 10
factorial(5) #Factorial of a number e.g 5!
abs(1/-2)    #Absolute values of a number 
2*pi/360     #Number of radian in one Babylonian degree of a circle

Remember R prints all very large or very small numbers in scientific notation.

Order of Precedence/ Operations

The R language also makes use of parentheses for grouping operations to follow the rules for the order of operations. for example

1 - 2/3   #It first computes 2/3 and then subtracts it from 1
(1-2)/3   #It first computes (1-2) and then divides it by 3

The R Language recognizes certain goofs, like trying to divide by zero, missing values in data, etc.

1/0       # Undefined, R tells it an infinity (Inf)
0/0       # Not a number (NaN) 
"one"/2   # Strings or characters is divided by a number

Further Reading: Computing Descriptive Statistics in R

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