R Tutorial

Vectors in R

A vector is the most basic data structure in R. It is a sequence of elements that are all of the same type. Vectors can store numeric values, characters, logical values, or other types, but all elements in a single vector must be of the same type.

Creating Vectors

Use the c() function to combine values into a vector.

# Numeric vector
numbers <- c(10, 20, 30, 40, 50)

# Character vector
fruits <- c("apple", "banana", "cherry")

# Logical vector
flags <- c(TRUE, FALSE, TRUE, TRUE)
  

Vector Types

• Numeric vectors: Contain numbers (e.g., 1, 2.5, -3).
• Character vectors: Contain text (strings).
• Logical vectors: Contain TRUE or FALSE values.

Accessing Vector Elements

Use square brackets [] with the index (starting at 1) to access elements.

fruits[2]        # "banana"

numbers[c(1, 3)]  # selects 1st and 3rd elements: 10 and 30

flags[flags == TRUE] # elements where value is TRUE
  

Vector Operations

Vectors support arithmetic and logical operations element-wise.

a <- c(2, 4, 6)
b <- c(1, 3, 5)

a + b          # adds elements: c(3, 7, 11)
a * 2          # multiplies each element by 2: c(4, 8, 12)
a > 3          # logical comparison: c(FALSE, TRUE, TRUE)
  

Important Vector Functions

• length(x) – returns number of elements
• sum(x) – sums numeric elements
• mean(x) – calculates average
• sort(x) – sorts elements
• unique(x) – returns unique elements

Summary

• Vectors hold elements of the same type.
• Use c() to create vectors.
• Access elements with square brackets [].
• Vectors support element-wise operations.
• Functions like length(), sum(), and mean() help analyze vectors.

Practice Exercises

• Create a numeric vector with 5 values and find its sum and mean.
• Create a character vector of your 3 favorite cities.
• Access the 2nd element of any vector.
• Create two numeric vectors and perform element-wise addition.