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This is the first lesson of CloudStat School, Lesson 1: Overview of R Language & CloudStat School.

The objective of this lesson is introducing R Language and how you can be a R programmer or a data analyst through CloudStat School.

At the end of this lesson 1, you will learn:

- What and Why is R Language.
- How to run CloudStat Console.
- Use CloudStat Console as a calculator.
- Some built-in mathematical functions.
- Integer Quotients and Modulo.
- Rounding (Up, down and nearest)

**1. Introduction****1.1 What is CloudStat School?**

An online platform for you to learn and do data analysis

with R Language collaboratively and interactively.

**1.2 What is R Language?**

R is an open source (free!) programming language

that has excellent statistical abilities.

R has Everything you need in terms of data analysis.

**1.3 Prerequisites & Preparations**

All you need is Internet Access! That’s all!

There is no download, installation, updates or maintenance needed.

**1.4 Alert!**

R is a language, like Italian, Dutch, Spanish, English, or Chinese.

If you try to proceed too rapidly, use the wrong reading material, or

have the wrong teacher, then, yes, mastering R may be challenging.

So be fun and enjoy the learning process!

**1.5 Overview**

You will see a console box at your left hand side.

Below is the output box. Anything you “Run”

in console box will be shown as a result in the output box.

There is a default command in the console box:

x = -100:100; plot(x^2)

Now, give it a try, just click “Run” to see what’s happening!

Yes! You’re plotting a quadratic function, x2 graph as below!

Let’s try some more.**Use this console as a calculator!** Type:

1+1

And click the “Run” button.

Simple math. 1+1 is 2. You will see something like:

> 1+1

[1] 2

Try more:

12+43

56-12

5*6

63/7

“Run” it!

You will get:

> 12+43

[1] 55

> 56-12

[1] 44

> 5*6

[1] 30

> 63/7

[1] 9

Let’s do it in one line.

Just remember separate them with semi-colons ;

12+43; 56-12; 5*6; 63/7

Then, click “Run” button to see the result.

You will see something like:

> 12+43; 56-12; 5*6; 63/7

[1] 55

[1] 44

[1] 30

[1] 9

Let’s try some built-in mathematical functions!

exp(12)

log(12)

sin(12)

Then, click “Run” button as before to see the output!

You will see

> exp(12)

[1] 162754.8

> log(12)

[1] 2.484907

> sin(12)

[1] -0.5365729

There are more! You can try:

log(x) = log to base e of x

exp(x) = antilog of x ex

log(x,n) = log to base n of x

log10(x) = log to base 10 of x

sqrt(x) = square root of x

cos(x) = cosine of x in radians

atan(x) = inverse trigonometric transformations

More…

Want to use π ? Please type:

pi

Output will be:

> pi

[1] 3.141593

Type:

cos(pi/2)

You will get:

> cos(pi/2)

[1] 6.123234e-17

The e-17 means times 10−17.

**Numbers with Exponents**

For very big numbers or very small numbers:

2.4e3 means 2400

4.8e-2 means 0.048

8.2+3.4i is a complex number with real (8.2) and imaginary (3.4) parts

Just try typing the red command into the console box to see the output!

**Modulo (Remainder)**

Now suppose we wanted to know the remainder,

(what is left over when 234 is divided by 7),

in maths this is known as **modulo.**

Use %% (percent, percent)

> 234 %% 7

[1] 3

**Integer Quotients**

How’s about the integer part of a division,

for last example, how many 7s are there in 234?

Use %/% (percent, divide, percent)

> 234 %/% 7

[1] 33

**Modulo** is very useful for testing if odd or even:

odd numbers have modulo 2 value 1

even numbers have modulo 2 value 0

> 7 %% 2

[1] 1

> 4 %% 2

[1] 0

You use **modulo** to test if one number,

is an exact multiple of some other number.

For instance:

to find out whether 72 is a multiple of 8 or 7, ask:

> 72 %% 8 == 0

[1] TRUE

> 72 %% 7 == 0

[1] FALSE

72 is a multiple of 8, not 7.

**Rounding**

a) Rounding down

> floor(3.4)

[1] 3

b) Rounding up

> ceiling(3.4)

[1] 4

c) Rounding to the nearest integer

> round(3.4, digits=0)

[1] 3

> round(3.5, digits=0)

[1] 4

**Shortcut**: Use round(x,0)

> round(3.5, 0)

[1] 4

So, hope you have learnt some of the basics!

Please join us @ CloudStat School Forum

to discuss the issues, i.e. problems, suggestions,

feedback about CloudStat School!

Please share about us to your friends too!

Thank you!

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