Language Basics.R

# R Language Basics

# Assignment operators
x <- "Hello World!"
y = "Hello World!"

#Implicit Printing
print(x)
x

# Creating variable
l <- TRUE
i <- 123L
n <- 1.23
c <- "ABC 123"
d <- as.Date("2001-02-03")

# Displaying Variables
l
i
n
c
d


# Creating a function
f <- function(x) { x + 1 }

# Invoking a function
f(2)

# Creating a vector
v <- c(1, 2, 3);
v

# Creating a sequence
s <- 1:5
s

# Creating a matrix
m <- matrix(
      data = 1:6,
      nrow = 2,
      ncol = 3)
m

# Creating an array
a <- array(
  data = 1:8,
  dim = c(2,2,2))
a


# Creating a list
l <- list(TRUE, 123L, 2.34, "abc")
l

# Creating a factor
categories <- c("Male", "Female", "Male", "Male", "Female")
factor <- factor(categories)
factor
levels(factor)
unclass(factor)

# Creating a data frame
df <- data.frame(
  Name = c("Cat", "Dog", "Cow", "Pig"),
  HowMany = c(5, 10, 15, 20),
  IsPet = c(TRUE, TRUE, FALSE, FALSE)
)
df

# Indexing data frames by row and column
df[1,2]

# Indexing data frames by row
df[1,]

# Indexing data frames by column
df[,2]
df[["HowMany"]]
df$HowMany

# Subsetting data frames
df[c(2, 4), ]
df[2:4, ]
df[c(TRUE, FALSE, TRUE, FALSE),]
df[df$IsPet == TRUE, ]
df[df$HowMany > 10, ]
df[df$Name %in% c("Cat", "Cow"), ]

# R is a vectorized language
1 + 2
c(1,2,3) + c(2,4,6)

# Named vs. ordered arguments
m <- matrix(data = 1:6, nrow = 2, ncol =3)
n <- matrix(1:6, 2, 3)
m == n 
identical(m, n)

# Installing pacakges
install.packages("dplyr")

# Loading packages
library("dplyr")

# Viewing help
?data.frame