# is for comments
R ignores everything that appears after the hash (#).
The assignment operator is symbol for less than followed by hash. (The blogger is creating a problem by giving strange interpretation of the symbol.)
#read files with labels in first row
read.table(filename,header=TRUE,sep=',') #read csv files
<- a="" c="" create="" data="" elements="" nbsp="" p="" specified="" vector="" with=""><- 1="" a="" c="" create="" data="" elements="" nbsp="" p="" to10="" vector="" with=""><- 10="" p=""><- a="" c="" create="" deviates="" item="" n="" nbsp="" normal="" of="" p="" random="" rnorm="" vector=""><- a="" added="" c="" create="" distribution="" each="" has="" item="" n="" nbsp="" p="" random="" runif="" that="" to="" uniform="" vector=""><- binomial="" create="" from="" n="" nbsp="" of="" p="" prob="" probability="" rbinom="" samples="" size="" the="" with=""><- and="" c="" combine="" into="" length="" nbsp="" of="" one="" p="" vector="" vectors="" x="" y=""><- 2="" a="" and="" cbind="" combine="" into="" matrix="" n="" nbsp="" p="" x="" y="">
mat[4,2] #display the 4th row and the 2nd column
mat[3,] #display the 3rd row
mat[,2] #display the 2nd column
subset(dataset,logical) #those objects meeting a logical criterion
subset(data.df,select=variables,logical) #get those objects from a data frame that meet a criterion
data.df[data.df=logical] #yet another way to get a subset
x[order(x$B),] #sort a dataframe by the order of the elements in B
x[rev(order(x$B)),] #sort the dataframe in reverse order
browse.workspace #a Mac menu command that creates a window with information about all variables in the workspace
Details
Input and display
#read files with labels in first row
read.table(filename,header=TRUE) #read a tab or space delimited file
read.table(filename,header=TRUE,sep=',') #read csv files
x <- a="" c="" create="" data="" elements="" nbsp="" p="" specified="" vector="" with="">To construct a vector
> c(1,2,3,4,5)
[1] 1 2 3 4 5
y <- 1="" a="" c="" create="" data="" elements="" nbsp="" p="" to10="" vector="" with="">
> x <- 1:5="" nbsp="" p="">> x
[1] 1 2 3 4 5
assign the values 1:5 to a vector named x:
> x <- 1:5="" p="">> x
[1] 1 2 3 4 5
n <- 10="" p="">x1 <- a="" c="" create="" deviates="" item="" n="" nbsp="" normal="" of="" p="" random="" rnorm="" vector="">y1 <- a="" added="" c="" create="" distribution="" each="" has="" item="" n="" nbsp="" p="" random="" runif="" that="" to="" uniform="" vector="">z <- binomial="" create="" from="" n="" nbsp="" of="" p="" prob="" probability="" rbinom="" samples="" size="" the="" with="">vect <- and="" c="" combine="" into="" length="" nbsp="" of="" one="" p="" vector="" vectors="" x="" y="">
mat <- 2="" a="" and="" cbind="" combine="" into="" matrix="" n="" nbsp="" p="" x="" y="">mat[4,2] #display the 4th row and the 2nd column
mat[3,] #display the 3rd row
mat[,2] #display the 2nd column
subset(dataset,logical) #those objects meeting a logical criterion
subset(data.df,select=variables,logical) #get those objects from a data frame that meet a criterion
data.df[data.df=logical] #yet another way to get a subset
x[order(x$B),] #sort a dataframe by the order of the elements in B
x[rev(order(x$B)),] #sort the dataframe in reverse order
browse.workspace #a Mac menu command that creates a window with information about all variables in the workspace
Rules of Names of Variables, Vectors and Matrices in R
Names must start with a letter or a dot. If you start a name with a dot, the
second character can’t be a digit.
Names should contain only letters, numbers, underscore characters (_),
and dots (.). Although you can force R to accept other characters in names, you
shouldn’t, because these characters often have a special meaning in R.
You can’t use the following special keywords as names:
• break
• else
• FALSE
• for
• function
• if
• Inf
• NA
• NaN
• next
• repeat
• return
• TRUE
• while
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