ls()— list currently loaded objects.
rm(object)— delete a currently loaded object.
summary(object)— find out about some object.
str(object)— find out even more about some object.
names(g)— gets the names of all columns in a dataframe.
g$gender— access a column by name.
g[,1]— access a column by number.
g[,'age']— access a column by name.
g[1,]— access a row.
g[4,2]— access a cell.
g[3:6,1:2]— access a block of cells.
g[g$gender=='f',] g[g$weight < 160,] g[g$gender=='m' & g$weight < 160,] g[g$gender=='f',2] g[g$gender=='f','major']
attach(object)— make the parts of some currently loaded object directly available, e.g.
g$genderis available as
detach(object)— make the parts unavailable again, except with the dataframe prefix, e.g.
search()— examine what objects are attached.
sd()— standard deviation.
tapply()— apply some function by factors to a dataframe.
t()— transpose a dataframe.
transform()— alter a dataframe in some way.
aggregate()— aggregate within some dataframe.
as.factor()— convert a list/vector of numbers into a factor.
is.factor()— test if something is a factor.
cut(vector,levels)— break a vector of numbers into a factor with n levels.