ClassMaterial/class_code/class_01_with_answers.R

In emeyers/SDS230: Tools for the class Data Exploration and Analysis

# 1.1 Basic arithmetic 
2 + 2
7 * 5


# 1.2 Assigning values to objects
a <- 4
b <- 7
z  <- a + b
z


# 1.3 Number journey 
a <- 7 
b <- 52 
x <- a * b 
x


# 2.1 Numeric, string and Boolean data types
a <- 7			
s <- "s is a terrible name for an object"
b <- TRUE

class(a)
class(s)



# 3.1 Functions 
sqrt(49)			
tolower("DATA is AWESOME!")

# 3.2 To get help information about a function or data set
? sqrt



# 4.1 Comments
# One can add comments to your code to describe what you are doing
sqrt(49)    # this takes the square root of 49



# 5.1 Vectors are ordered sequences of numbers or letters
# The c() function is used to create vectors

v  <-  c(5, 232, 5, 543)	
s  <-  c("statistics", "data", "science", "fun")		


# 5.2 One can access elements of a vector using square brackets []
s[4]         # what will the answer be?    


# 5.3 We can get multiple elements from a vector too
s[c(1, 2)]


# 5.4 One can assign a sequence of numbers to a vector
z <- 2:10
z[3]	

# 5.5 One can test which elements are greater than a value
z > 3

# 5.6 Can add names to vector elements
names(v) <- c("first", "second", "third", "fourth")


# 5.7 One can also apply functions to vectors
z <- 2:10
sqrt(z)
mean(z)