Use levels and ordered parameters with the factor() function to create an ordered factor in R.
What is the as.factor() function in R?
Key takeaways:
R factors provide a structured way to represent and analyze categorical data.
as.factor(x)converts vectors into factors, which is essential for statistical modeling and summarizing categorical data.
as.factor(x)is the syntax, wherexis the vector to be converted.It works with string, numerical, and mixed-type vectors, converting them into factors with unique levels.
Use
table()to count occurrences of each factor level for effective data analysis.
Categorical data is everywhere. Terms such as “pass,” “fail,” “high,” and “low” are often used when analyzing student performance, customer preferences, or product reviews. Although these data may appear manageable at first glance, summarizing, counting, and statistically analyzing raw categorical data is challenging and requires a systematic approach. This is where factors come into play.
What are the R factors?
Factors in R is a data structure used to categorize data. They are used to store data that can be divided into discrete categories, such as “Male” and “Female,” or “Low,” “Medium,” and “High.” Also, factors have levels, which are the unique values that a factor can take. For example, a factor representing “Grade” might have levels “Pass” and “Fail.”
To get the benefit of R factors, we need to convert categorical data into factors first. In this Answer, we’ll explore as.factor() function offered by R and its benefits.
The as.factor() function
The as.factor() function in R is used to convert a vector object to a factor. Categorical conversion is essential for many R statistical models, including ANOVA and regression, as well as for data summarization tasks like calculating frequencies.
Syntax
The syntax of the as.factor() function is given below:
as.factor(x)
The as.factor() function takes a single and mandatory parameter value x, which represents the vector object to be converted.
Return value
The as.factor() function returns a factor object.
Apply the as.factor() function to the string vector
Let’s apply the as.factor() function to the string vector:
# creating a vector variablemyvector <- c("Tall", "Short", "Tall", "Short")# calling the as.factor() functionas.factor(myvector)
The output of the code above shows that the output is a factor object with two levels of factor Short and Tall.
Apply the as.factor() function on the numerical vector
Let’s apply this function to the numerical vector:
# creating a vector variablemyvector <- c("1", "2", "3", "4", "1.5", "10.5")# calling the as.factor() functionas.factor(myvector)
In the code above, we call the as.factor() function on an integer vector, ultimately converting it to a factor object.
Apply as.factor() function on the mixed-type vector
Let’s utilize this function with the mixed-type vector, which includes both strings and numerical values:
# creating a vector variablemyvector <- c("1", "1", "3", "3", "Tall", "Tall", "Short")# calling the as.factor() functionas.factor(myvector)
In the code above, we call the as.factor() function on the mixed-type vector, ultimately converting it to a factor object.
Summarizing categorical data with as.factor() in R
We can efficiently summarize a vector by calculating the frequency of each categorical value in the vector using the table() method. Let’s apply this function to the resulting factor.
Data are just summaries of thousands of stories—tell a few of those stories to help make the data meaningful. — Dan Heath
# creating a vector variablemyvector <- c("Short", "Short", "Tall", "Tall", "Tall", "Tall", "Short")# calling the as.factor() functionas.factor(myvector)# Summarize the factor using table()height_summary <- table(myvector)# Print the summaryprint(height_summary)
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Frequently asked questions
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