# R in Action (2nd ed): Chapter 2
# Creating a dataset
#-----------------------------------------------------

#  Creating vectors
a <- c(1, 2, 5, 3, 6, -2, 4)
b <- c("one", "two", "three")
c <- c(TRUE, TRUE, TRUE, FALSE, TRUE, FALSE)

# Using vector subscripts
a <- c(1, 2, 5, 3, 6, -2, 4)
a[3]
a[c(1, 3, 5)]
a[2:6]                     

# Creating Matrices
y <- matrix(1:20, nrow=5, ncol=4)
y
cells    <- c(1,26,24,68)
rnames   <- c("R1", "R2")
cnames   <- c("C1", "C2") 
mymatrix <- matrix(cells, nrow=2, ncol=2, byrow=TRUE,
                   dimnames=list(rnames, cnames)) 
mymatrixs
mymatrix <- matrix(cells, nrow=2, ncol=2, byrow=FALSE,
                   dimnames=list(rnames, cnames))
mymatrix

# Using matrix subscripts
x <- matrix(1:10, nrow=2)
x
x[2,]
x[,2]
x[1,4]
x[1, c(4,5)]

# Creating an array
dim1 <- c("A1", "A2")
dim2 <- c("B1", "B2", "B3")
dim3 <- c("C1", "C2", "C3", "C4")
z <- array(1:24, c(2,3,4), dimnames=list(dim1, dim2, dim3))
z

# Creating a dataframe
patientID <- c(1, 2, 3, 4)
age <- c(25, 34, 28, 52)
diabetes <- c("Type1", "Type2", "Type1", "Type1")
status <- c("Poor", "Improved", "Excellent", "Poor")
patientdata <- data.frame(patientID, age, diabetes, status)
patientdata

# Specifying elements of a dataframe
patientdata[1:2]
patientdata[c("diabetes","status")]
patientdata$age                       

# Using factors
patientID <- c(1, 2, 3, 4)
age <- c(25, 34, 28, 52)
diabetes <- c("Type1", "Type2", "Type1", "Type1")
status <- c("Poor", "Improved", "Excellent", "Poor")
diabetes <- factor(diabetes)
status <- factor(status, order=TRUE)
patientdata <- data.frame(patientID, age, diabetes, status)
str(patientdata)                               
summary(patientdata)

#  Creating a list
g <- "My First List"
h <- c(25, 26, 18, 39)
j <- matrix(1:10, nrow=5)
k <- c("one", "two", "three")
mylist <- list(title=g, ages=h, j, k)
mylist