R as a calculator

• R can be used like a calculator type the following into your script.  To run it when your cursor is on the line in the script press Ctrl Enter

1 + 1

• The console will give out the answer as 2.  The square brackets is the index number of the answer. In this case the answer is only one value

> 1 + 1
[1] 2

• R follows the rules as any calculator.  In your script calculate the following

1+1
20*5
(45*3)+3.7
2^2
pi
(30/90)*100

• The output will be as below

> 1+1
[1] 2
> 20*5
[1] 100
> (45*3)+3.7
[1] 138.7
> 2^2
[1] 4
> pi
[1] 3.141593
> (30/90)*100
[1] 33.33333

R functions

• R is made up of thousands of functions that you use to manipulate and analyse your data.   They are the equivalent to maths functions in Excel e.g. STDEV(), SUM(), MEAN()

• A collection of themed R functions for e.g. a data type, or an analysis type is called a package
• R has thousands and thousands of packages to integrate with propriety software (ArcGIS, Stata), other tools (Twitter, SQL) and multiple data types (.txt, .csv, .sav) including compressed file formats (e.g. NetCDF)
• Each function has a number of arguments that are conditions for how you apply or run the function.  All R functions follow the same format:
  

  Function_name(arg1, arg2, arg3...)

• R has a wonderful help file to show you exactly how to use each function and argument....it even gives examples for you to work through.