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Unformatted text preview: as) Variable information
is.na(x), is.null(x), is.array(x), is.data.frame(x),
is.numeric(x), is.complex(x), is.character(x),
... test for type; for a complete list, use methods(is)
length(x) number of elements in x
dim(x) Retrieve or set the dimension of an object; dim(x) < c(3,2)
dimnames(x) Retrieve or set the dimension names of an object
nrow(x) number of rows; NROW(x) is the same but treats a vector as a onerow matrix
ncol(x) and NCOL(x) id. for columns
class(x) get or set the class of x; class(x) < "myclass"
unclass(x) remove the class attribute of x
attr(x,which) get or set the attribute which of x
attributes(obj) get or set the list of attributes of obj Data selection and manipulation
which.max(x) returns the index of the greatest element of x
which.min(x) returns the index of the smallest element of x
rev(x) reverses the elements of x
sort(x) sorts the elements of x in increasing order; to sort in decreasing
order: rev(sort(x))
cut(x,breaks) divides x into intervals (factors); breaks is the number
of cut intervals or a vector of cut points
match(x, y) returns a vector of the same length than x with the elements
of x which are in y (NA otherwise)
which(x == a) returns a vector of the indices of x if the comparison operation is true (TRUE), in this example the values of i for which x[i]
== a (the argument of this function must be a variable of mode logical)
choose(n, k) computes the combinations of k events among n repetitions
= n!/[(n − k)!k!]
na.omit(x) suppresses the observations with missing data (NA) (suppresses the corresponding line if x is a matrix or a data frame)
na.fail(x) returns an error message if x contains at least one NA unique(x) if x is a vector or a data frame, returns a similar object but with
the duplicate elements suppressed
table(x) returns a table with the numbers of the differents values of x
(typically for integers or factors)
subset(x, ...) returns a selection of x with respect to criteria (...,
typically comparisons: x$V1 < 10); if x is a data frame, the option
select gives the variables to be kept or dropped using a minus sign
sample(x, size) resample randomly and without replacement size elements in the vector x, the option replace = TRUE allows to resample
with replacement
prop.table(x,margin=) table entries as fraction of marginal table Math
sin,cos,tan,asin,acos,atan,atan2,log,log10,exp
max(x) maximum of the elements of x
min(x) minimum of the elements of x
range(x) id. then c(min(x), max(x))
sum(x) sum of the elements of x
diff(x) lagged and iterated differences of vector x
prod(x) product of the elements of x
mean(x) mean of the elements of x
median(x) median of the elements of x
quantile(x,probs=) sample quantiles corresponding to the given probabilities (defaults to 0,.25,.5,.75,1)
weighted.mean(x, w) mean of x with weights w
rank(x) ranks of the elements of x
var(x) or cov(x) variance of the elements of x (calculated on n − 1); if x is
a matrix or a data frame, the variancecovariance matrix is calculated
sd(x) standard deviation of x
cor(x) correlation matrix of x if it is a matrix or a data frame (1 if x is a
vector)
var(x, y) or cov(x, y) covariance between x...
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This document was uploaded on 04/10/2014.
 Fall '14

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