Course notes: Introduction to R

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작동 방식

오른쪽 편집기에는 연습 문제를 해결하기 위해 R 코드를 입력해야 합니다. '답변 제출' 버튼을 누르면, 각 코드 줄이 R에 의해 해석되고 실행되며, 코드가 올바른지 여부에 대한 메시지를 받게 됩니다. R 코드의 출력은 오른쪽 하단 콘솔에 표시됩니다.

R은 주석을 추가하기 위해 # 기호를 사용합니다. 이렇게 하면 여러분과 다른 사람들이 R 코드의 내용을 이해할 수 있습니다. 마치 트위터처럼 말이죠! 주석은 R 코드로 실행되지 않으므로 결과에 영향을 주지 않습니다. 예를 들어, 오른쪽 편집기에서 3 + 4 계산은 주석입니다.

또한 콘솔에서 직접 R 명령을 실행할 수도 있습니다. 이는 R 코드를 실험하는 좋은 방법입니다. 왜냐하면 제출한 내용이 올바른지 확인되지 않기 때문이죠.

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# Add your code snippets here
# Calculate 3 + 4
3 + 4

# Calculate 6 + 12
6 + 12

Arithmetic with R

In its most basic form, R can be used as a simple calculator. Consider the following arithmetic operators:

Addition: +
Subtraction: -
Multiplication: *
Division: /
Exponentiation: ^
Modulo: %%

The last two might need some explaining:

The ^ operator raises the number to its left to the power of the number to its right: for example 3^2 is 9.
The modulo returns the remainder of the division of the number to the left by the number on its right, for example 5 modulo 3 or 5 %% 3 is 2.

With this knowledge, follow the instructions to complete the exercise.

7%%4

# An addition
5 + 5 

# A subtraction
5 - 5 

# A multiplication
3 * 5

 # A division
(5 + 5) / 2 

# Exponentiation
3^3

# Modulo
7%%4

Variable assignment

A basic concept in (statistical) programming is called a variable.

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_var with the command

my_var <- 4

# Assign the value 42 to x
x <- 56

# Print out the value of the variable x
x

Variable assignment (2)

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

# Assign the value 5 to the variable my_apples
my_apples <- 5

# Print out the value of the variable my_apples
my_apples

Variable assignment (3)

Every tasty fruit basket needs oranges, so you decide to add six oranges. As a data analyst, your reflex is to immediately create the variable my_oranges 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

# Assign a value to the variables my_apples and my_oranges
my_apples <- 5


# Add these two variables together
my_oranges <- 3

# Create the variable my_fruit
my_fruit <- my_apples + my_oranges
minus_furit <- my_apples - my_oranges
mul_fruit <- my_apples * my_oranges
div_fruit <- my_apples / my_oranges

my_fruit
minus_furit
mul_fruit
div_fruit

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 and a character variable to the variable my_fruit. This is not possible.

룰렛의 승리/패배를 변수 roulette_vector에 할당하세요. $24를 잃은 후에 $50을 잃었으며, $100을 얻었고, $350을 잃었으며, $10을 얻었습니다.

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