**Mathew Analytics LLC » R**, and kindly contributed to R-bloggers)

Vectors are a basic data structure in R and are created using the c()

function. Unlike data frames and lists, the elements of a vector must be of

the same mode.

Functions can be used on a vector. For example, length(x) can be used to find the number of elements in x. Furthermore, conditions can be used to determine if the elements of a vector meet a certain criteria.

The elements of a vector can be selected by using the name of the vector

followed by an index vector in square brackets. Positive index values specify

the values to be included. Negative index values specifiy the values to be

excluded. Furthermore, vectors with a names attribute can be indexed using

its names.

# Creating vectors with the c() function

vecone <- c(1,3,5,7,9)

vectwo <- c(“KS”, “IA”, “NY”, “NY”, “FL”)

vecthree <- c(vecone, 0, vecone)mode(vecone)

mode(vectwo)

mode(vecthree)# Using functions on a vector

length(vecone)

length(vectwo)

length(vecthree)max(vecone)

min(vecone)# Vector arithmetic

vecone + vecone

vecone * 2

vecone^2# Using conditions

vecon > 4

vecone > 4 & vecone < 9

vectwo == “KS”

vectwo != “KS”

vectwo[vectwo != “KS”]

which(vectwo != “KS”)

vectwo# Indexing a vector

vecone

vectwo

vecone[1]

vectwo[1]

vecone[3]

vectwo[3]

vecone[1:3]

vectwo[1:3]

vecone[length(vecone)]

vectwo[length(vectwo)]vecone[-2]

vectwo[-2]

vecone[-c(1:3)]

vectwo[-c(1:3)]

vecone[-length(vecone)]

vectwo[-length(vectwo)]# Indexing a vector with names

newvec <- c(1,6,8,9,13,14)

names(newvec) <- c(“Var1″, “Var2″, “Var3″, “Var4″, “Var5″, “Var6″)

newvec

newvec[“Var3″]

newvec

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