R is a command-line language, which means that you type commands into the console and R responds with output. Commands in R typically involve calling functions to run on objects Objects are created using assignment statements Try typing these examples in the console. Hit enter after typing a command to run it:

x <- 5
y = 7
z = x + y
print(x * y); print(z)

x == 5
x == y
x != y

word1 = "hello"
word2 = "world"
word3 = paste(word1, word2)
print(word3)
# this line is a comment

Easy Mistakes

R is case sensitive. Variable names cannot start with numbers or have spaces. Try running these examples that will give errors

#these will have errors
a = 10
print(A)
4w = 99
new word = "words"

#Fixes:
w4 = 99
new_word = "words"
newWord = "words2"

Built-In Functions

R has many built-in functions that can make things much easier!

Try some of these examples by running them in an R Script.

Go to File > New File > R Script to make an empty script, and then type this text. Hitting enter in here moves you to a new line.

To run a line of code, click on it and hit Ctrl + Enter (Windows) or Command + Enter (Mac), or click “Run”. To run multiple lines, highlight them and then hit Ctrl + Enter, Command + Enter, or “Run”

cat("first", "word")
numbers = c(12, 13.72, 86.002)
length(numbers)
mean(numbers)
sd(numbers)
str(numbers)
summary(numbers)
View(numbers)

Conditionals and Loops

Sometimes you only want R to run commands under certain conditions. Try this example. This code only prints “yes” if the value you are checking is equal to 5.

x <- 5
if(x == 5) {
  print("Yes")
} else {
  print("No")}

You can also use loops to perform actions a set number of times. Say for example, you wanted to count how many times a subject’s response was equal to 5…

tally = 0
data <- c(3,1,5,2,2,5,4,5) 
  #the c() function creates a vector (like a column)
for (x in 1:length(data)){ 
  #run x times, from 1 to the end of the #data vector
  if (data[x] == 5) {
    tally = tally + 1
    print("yes")
  }
  else {
    print ("no")
  }
}
print(tally)