print("Hello, World!")
#cat("\nWelcome to R Programming Language ")

if (FALSE) {
    'This is a demo for multi-line comments and it should be put inside either and
      single OR double quot'
}

myString <- "string in r programming"
print(myString)



#######################################################################
#Data Types in R 
#logical (true or false)
l <- TRUE
print(class(l))

#numeric 
n <- 23.7
print(class(n))

#integer
i <- 2L
print(class(i))

#complex number
c <- 2+3i
print(class(c))

#character
ch <- "TRUE"
print(class(ch))

#########################################################################33
#create a vector
fruits <- c('apple', 'orange', 'grapes', 'mango')
print(fruits)
#check the data type use 
print(class(fruits))

#creating a list
#c is a function which lets us combine elements into a vector
list_r <- list(c(1, 2, 5), 12.4, 'sin')
print(list_r)
print(class(list_r))

#create a matrix
M = matrix(c('s', 'a', 'e', 't', 'w', 'a'), nrow=3, ncol=2, byrow=TRUE)
print(M)
print(class(M))

#create an array
arr <- array(c('green', 'red'), dim=c(3,3,2))
print(arr)
##################################################################################
#factor in r
#factor()
x <- c("Banana", "Apple", "Pineapple", "Banana", "Apple")
print(x)
Flavors <- factor(x)
#print(Flavors)
print(class(Flavors))

##################################################################################
#create a DataFrame
BMI <- data.frame(
  names= c('Matthew', 'Alice', 'Nazim'),
  gender= c('male', 'female', 'male'),
  height= c(176, 165.2, 172),
  age = c(19, 20, 34)
)
print(BMI)

###################################################################################
#variables
#Assignment using equal operator 
var.1 = c(0,1,2,3)
#Assignment using leftward operator
var.2 = c('learn', 'R')
#Assignment using forward operator
c(TRUE, 1) -> var.3
#var.3 <- c(TRUE, 1) means the same thing as the line above
print(var.1)
cat('var.1 is ', var.1, '\n')
cat('var.2 is ', var.2, '\n')
cat('var.3 is ', var.3, '\n')

#how to check variables
#character
var_x <- "Hello"
cat("The class of var_x is ",class(var_x),"\n")
#numeric
var_x <- 34.5
cat("Now the class of var_x is ",class(var_x),"\n")
#integer
var_x <- 27L
cat("Next the class of var_x becomes ",class(var_x),"\n")

#Finding variables
#print(ls())
print(ls(pattern="var"))
print(ls(all.name=TRUE))

#Deleting variables
rm(var.3)
#print(var.3)

rm(list=ls())
print(ls())
######################################################################################
#Operators in R
a = c(2, 3.3, 1.5)
b = c(2, 4.5, 6)
sum = a+b
print(sum)

sub = a-b
cat('the subtraction of a and b is: ', sub, '\n')

mul = a*b
print(mul)

div = a/b
print(div)

rem = a%%b
print(rem)

exp = a^b
print(exp)

#Relational Operators [<, >, ==, <=, >=]
print(a<=b)

#Colon Operators {display the range}
v <- 2:10
print(v)
#######################################################################################
#Decision Making in R --> Conditions using if-else
x <- 20
if(is.integer(x)){
  print('x is an integer')
}else{
  print('x is not an integer')
}

#Repeat loop
v <- c('learn', 'loop')
count <- 5
repeat{
  print(v)
  count <- count + 1
  if(count>10){
    break
    
  }
  
}

#While loop
print('While loop')
v <- c("Hello", "while loop")
count <- 2
while(count<7){
  print(v)
  count <- count + 1
}

#For loop
v <- LETTERS[1:26]
for(i in v){
  print(i)
}

#################################################################################
#using BREAK statement to end loop
x <- 1:5
for (val in x) 
{
 if (val == 3)
  {
  break
  } #END If
 print(val) 
} #END For
cat("==============================================\n")
#using NEXT statement to skip loop step
x <- 1:5
for (val in x) 
{
 if (val == 3)
 {
  next
 } #END If
 print(val)
} #END For
###################################################################################
#Create a function to print squares in sequence
new.function <- function(a){
  for(i in 1:a){
    b <- i^3
    print(b)
  }
}
new.function(5)

#example2 --> function
new.function <- function(a, b, c){
  result <- a*b*c
  print(result)
}

#call the function
new.function(a=2, b=3, c=4)
###############################################################################

#install packages in R
#install.packages("XML")

##############################################################################

#Data Reshaping
#create vector objects
city <- c("Sydney", "Melbourne", "Canberra", "Perth")
state <- c("NSW", "VIC", "ACT", "WA")
zipcode <- c(2000, 2600, 3000, 5000)
#combine the three vectors into dataframe
addresses <- cbind(city, state, zipcode)
#print(addresses)

#print a header
cat("# # # # The First data frame\n")
print(addresses)

#create another dataframe
new.address <- data.frame(
  city = c("Darwin", "Brisbane", "Adelaide", "Hobert"),
  state = c("NT", "QLD", "SA", "TAS"),
  zipcode = c(4000, 5000, 8000, 7000),
  stringsAsFactors =FALSE
)

#print a header
cat("# # # # The Second data frame\n")
print(addresses)

#Print the data frame
print(new.address)

#combine all rows in both dataframes
all.addresses <- rbind(addresses, new.address)
print(all.addresses)