R Factor

Factor

• A Factor is a vector object used to specify a discrete classification (grouping) of the components of other vectors of the same length

• Factor variables are categorical variables that can be either numeric or string type

• R provides both ordered and unordered factors

//Syntax:
	>factor(x)

	>as.factor(x)

x can be a vector, list, matrix or a dataframe

>is.factor(x)

it checks if an object is a factor or not and returns a Boolean value

var <- c(1,0,1,0,0,1,0,1,1,0)
	var1 <- factor(var)
	is.factor(var1)
	[1]TRUE

	var1
	[1] 1 0 1 0 0 1 0 1 1 0
	Levels: 0 1

	var2 <- as.factor(var)
	var2
	[1] 1 0 1 0 0 1 0 1 1 0
	Levels: 0 1

Consider the following data with different types of waste and convert it to a factor using as

x <- c('organic', 'metal', 'plastic',
	+  'plastic', 'organic', 'metal', 'metal',
	+  'metal', 'organic', 'paper', 'plastic',
	+  'glass', 'mixed', 'e-waste', 'glass',
	+  'glass', 'e-waste', 'glass', 'metal')

Output:

Factors give us the following information

• The Levels gives us the unique values in the dataset

• table(x) gives us the frequency of individual items available

• level(x) gives us the levels of the factor

Ordered Factor

In an Ordered Factor, logical flag is set to determine if the levels should be regarded as ordered or not

Consider a vector named ‘depth’. By using the option ‘ordered = TRUE’, it can be converted to an ordered factor

#UnOrdered Factors
	depth <- c("Low", "High", "Medium", "High",
	   "High", "Medium", "Medium", "Low",
	   "Low", "Low", "High", "Low")
	depth.f <- factor(depth)

Output:

#Ordered Factors
	depth.f <- factor(depth, levels = c("Low", "Medium", "High"), ordered = TRUE)

Output: