chap1-variable-assignment

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Variable assignment(1)

• A basic concept in (statistical) programming is called a varibale.
• A variable allows you to store a value (e.g.4) or an object (e.g. a function description) in R. You can then later use this variable’s name to easily access the value or the object that is stored within this variable.
• You can assign a value 4 to a variable my_variable with the command: my_variable = 4.

Exercises1

> # Assign the value 42 to x
> x = 42
> # Print out the value of the variable x
> x
[1] 42

Variable assignment(2)

• Suppose you have a fruit basket with five apples. As a data ananlyst in training, you want to store the number of apples in a variable with the name my_apples.

Exercises2

> # Assign the value 5 to the variable called my_apples
> my_apples <- 5
> # Print out the value of the variable my_apples
> my_apples
[1] 5

Variable assignment(3)

• Every tasty fruit basket needs oranges, so you decide to add six oranges. As a data ananlyst, your reflex is to immediately create the variable my_orange and assign the value 6 to it. Next, you want to calculate how many pieces of fruit you have in total. Since you have given meaningful names to these values, you can now code this in a clear way:my_apples + my_oranges.

Exercise3

> # Assign a value to the variables called my_apples and my_oranges
> my_apples = 5
> my_oranges = 6
> # Add these two variables together and print the result
> print(my_apples + my_oranges)
[1] 11
> # Create the variable my_fruit
> my_fruit = my_apples + my_oranges

Apples and oranges

• Common knowledge tells you not to add apples and oranges. But hey, that is what you just did, no:-)? The my_apples and my_oranges variables both contained a number in the previous exercise. The + operator works with numeric variables in R. If you really tried to add “apples” and “oranges”, and assigned a text value to the variable my_oranges (see the editor), you would be trying to assign the addition of a numeric a character variable to the variable my_fruit. This is not possible.

Exercise4

> # Assign a value to the variable called my_apples
> my_apples = 5
> # Print out the value of my_apples
> my_apples
[1] 5
> 
> # Add a character
> my_oranges = 6
> my_oranges
[1] 6
> 
> # New variable that contains total amount of fruit
> my_fruit = my_apples + my_oranges
> my_fruit
[1] 11

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