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

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

> 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.

Next section

The R help function