Section 5 Factor: Ordinal

5.1 Ordinal Factor

Example vector: x <- rep(c('L','M','H'), length=30)

Function	Explanation	Example
factor	Make a vector to factor	factor(x=x, levels=c(L,M,H), labels=c(Low,Med,High))
as.factor	Convert a vector to factor	as.factor(x)
ordered	Make a vector to an ordered factor	ordered(x=x, levels=c(L,M,H), labels=c(Low,Med,High))
as.ordered	Convert a vector to ordered factor	as.ordered(x)
levels	Get the labels of the factor levels	levels(x)
nlevels	Get the number of levels of a factor	nlevels(x)

Note: In the above table, levels and labels of a factor should be with single or double quotes.

5.2 Example

y <- rep(c('L','M','H'), length=30)

o1y <- as.ordered(x=y)

y
o1y

levels(o1y)
nlevels(o1y)
as.numeric(o1y)
table(o1y)
attributes(o1y)


o2y <- ordered(x=y, levels=c('L','M','H'), labels=c('Low','Med','High'))

y
o2y

levels(o2y)
nlevels(o2y)
as.numeric(o2y)
table(o2y)
attributes(o2y)