Lecture III: Data Handling

  • R is case sensitive

  • Anything that follow the # symbol is intepreted as a comment and is ignored by R

  • in R, commands are generally seprated by a new line, but you can also use a semicolon

  • If a continuation prompt + appears in the console after you execute your code, this means that you haven’t completed your code correctly

  • This often happens if you forget to close a bracket and is especially common with nested brackets

Creating an Object

Simply name an object

To Name an object use (n←22)

  • the ← symbol is callled assignment operator

  • The assignment operator is a composite symbol comprised of a less than symbol and a hyphen

  • Not equal to is an exclamation point and an equation sign

  • When an object is created, it will get diplayed in the envrionment

Creating a Object Using Data Types in R

1.1 Numberic

  • REprensents wole and decimal numbers

  • Default type fro numbers in R

1.2 Integer

  • Whole numbers only

  • Must be explcity marked with an

  • Asking class and typeof is the same thing

Naming an object

  • keep is short and infromative

  • area_of_the_triangle (using underscores)

  • AreaOfTheTriangle (utilising case sensitivity)

  • area.of.the.triangle

LImitations

  • an object name cannot start with a number or a dot folloed by a number (i.e. 2my_variable or /2my_variable)

  • you should also avoid using non-alphanumeric characters in your object names

  • In addition, make sure you don’t name your objects with reserved words (e.g. TRUE, NA)

  • It’s never good a idea to give your object the same name as a built-in function (such as mean, class, data)

Creating a vector

  • the c() function is short for concatenate and we use it to join together a series of values and store them in a data structure called a “vector“

  • When you use a function in R, the function name is always followed by a pair of round brackets

  • The arguments of a function are palced inside the round brackers and are seprated by commas

Operating Vectors

  • Positional index: to extract elements based on their position we simply write the position inside the []

  • Logical index: Logical expression will help if you are looking for more than one piece of data

Creating a matric

matrix (1:6,2,3)

matrix(data=,,,)