#examples for PSY533 Lab 10//8/08 Ted Walls URI

#setting up a vector based on a sequence

x = seq(0, 300, by=10)
x

#some vector arithmetic
y = x/2
y

#a correlation
cor(x,y)

plot(x,y)

#creating the vector length (n)
length(x)

#generating a normal distribution
p = rnorm(31, 10, 2) #n, mu, sigma
p

#showing no association of x and q
cor(x,p)
plot(x,p)

# If statements in R--no 'then'  <- means =
x <- 4
if (x > 3) y <- 3 * x else y <- 4 * x
y

#missing values in R--shows missing values as NA

x <- NULL  #vector with no elements
x[seq(2,20,2)] <- seq(2,10,2)
x

#use a command to detect missing values
is.na(x)
#or the opposite 'not' is.na --R uses !
!is.na(x)

x[which(is.na(x))] #show the numbers in x that are missing
x

#show the mean of just the values that are not missing
mean(x, na.rm=TRUE)  #the rm function removes the missing values

hist(x)

x
#drop some information from x with if statement
if (x < 8) y = x
y