# This document is from Stat 135, Spring 07
# It covers some basic R features inclding:
# Vectors, Assignments, extraction, and getting help

# You can make comments like this

# Equality means assigning the thing on the right to the left

a = 3

# Alternatively, one can use an arrow
a <- 3
6 -> b

# Just don't do this
3 = a

# There are several data structures, we first consider vectors

scoresM = c(5,8,3,5,2)
vec = 1:5

scores
vec
# or all at once
scores; vec

# note that R can be used as a calculator

2^4 - 1

# Most functions that operate on scalars operate  
# pointwise on vectors

(1:10)^2; exp( scoresM ); 1:10 + 1:10

a+b

ls() # see what is in your workspace
rm(a) # remove an object
a+b # doesn't work because you removed a

# you can paste things together and extract from them

vec1 = 1:10
vec2 = c(3,7,14)
vec3 = c( vec1, vec2 )

vec3
vec3[12]
vec3[7:12]
vec3[-(7:12)]

# we can generate a vector of random numbers

data = rnorm(10^4)
data
hist(data)

################### HOW TO GET HELP ###################

?rnorm
help(rnorm)
# both are the same, you can also enter up top

# If you aren't using a GUI, then open the 
# browser and go to search engine and keywords

help.start()

# note how there are default values

rnorm(10,50)

# 10 normals with mean 50 and variance 1

########################################################
# someone tells you about the function hist

hist(data)

# someone tells you about the function truehist
truehist(data)

# But you get an error
?truehist
# then try
help.search('truehist')

#the indication is that MASS needs to be added
library(MASS)
truehist(data)