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# Lec 1

ls() # lists whats in workspace
head(dat) # shows first entries of dat
tail(dat) # shows last entries of dat
rep(foo, n) # repeats foo n times
c() # collects items into one vector
class(dat) # shows the class of dat
dat$sex # only on data.frames: selects the sex vector of dat
table() # creates a one or two way table
scan() # reads in data from any source. be careful with its options
'<-' '=' # assignment operators
dim() # the dimensions of a matrix or data.frame, doesn't work on vectors

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# Lec 2
read.table() # reads in a file as a data.frame
read.csv() # reads in a .csv file as a data.frame
getwd() # displays your current working directory
setwd() # sets your working directory
head(dat) # displays first elements of dat
tail(dat) # displays last elements of dat
names(data.frame) # displays column names of data.frame
str(dat) # displays attributes of dat
unique(dat) # returns unique elements of dat
length(dat) # length of a vector
x[index] # returns x indexed by numbers contained in 'index'
is.na(dat) # checks for missing / NA elements of dat
which(test) # returns indices of true elements
ifelse(test, yes, no) # can be used to created binary variables
write.table # writes an R object to a file