What Does StringsAsFactors Mean In R?

Is age a categorical variable?

There are two types of variables: quantitative and categorical.

Categorical variables take category or label values and place an individual into one of several groups.

In our medical example, age is an example of a quantitative variable because it can take on multiple numerical values..

How do you describe a categorical variable?

In statistics, a categorical variable is a variable that can take on one of a limited, and usually fixed, number of possible values, assigning each individual or other unit of observation to a particular group or nominal category on the basis of some qualitative property.

How do I recode a categorical variable in R?

Recoding a categorical variable The easiest way is to use revalue() or mapvalues() from the plyr package. This will code M as 1 and F as 2 , and put it in a new column.

How do I subset data in R?

So, to recap, here are 5 ways we can subset a data frame in R:Subset using brackets by extracting the rows and columns we want.Subset using brackets by omitting the rows and columns we don’t want.Subset using brackets in combination with the which() function and the %in% operator.Subset using the subset() function.More items…•

What are levels in R?

levelsLevels Attributes. levels provides access to the levels attribute of a variable. … Usage. levels(x) levels(x) <- value.Arguments. x. ... Details. Both the extractor and replacement forms are generic and new methods can be written for them. ... References. ... See Also. ... Aliases.

What is a categorical variable in R?

Factors are variables in R which take on a limited number of different values; such variables are often referred to as categorical variables. … In a categorical variable, the value is limited and usually based on a particular finite group. For example, a categorical variable can be countries, year, gender, occupation.

How do I convert numeric to factor in R?

For converting a numeric into factor we use cut() function. cut() divides the range of numeric vector(assume x) which is to be converted by cutting into intervals and codes its value (x) according to which interval they fall. Level one corresponds to the leftmost, level two corresponds to the next leftmost, and so on.

What is the difference between character and factor in R?

The function character() is reserved for alphabetic characters (always categorical). The function factor() is reserved for alphanumeric (alphabetic and numeric) variables (always categorical). You can store everything as a factor or a character without loss of information.

How do you change factor levels in R?

One way to change the level order is to use factor() on the factor and specify the order directly. In this example, the function ordered() could be used instead of factor() . Another way to change the order is to use relevel() to make a particular level first in the list.

What does factor mean in R?

Conceptually, factors are variables in R which take on a limited number of different values; such variables are often refered to as categorical variables. Factors in R are stored as a vector of integer values with a corresponding set of character values to use when the factor is displayed. …

How do I remove a factor in R?

Removing Levels from a Factor in R Programming – droplevels() Function. droplevels() function in R programming used to remove unused levels from a Factor. droplevels(x, exclude = if(anyNA(levels(x))) NULL else NA, …)

What does data frame do in R?

Data Frames The function data. frame() creates data frames, tightly coupled collections of variables which share many of the properties of matrices and of lists, used as the fundamental data structure by most of R’s modeling software.

How do I label values in R?

To understand value labels in R, you need to understand the data structure factor. You can use the factor function to create your own value labels. Use the factor() function for nominal data and the ordered() function for ordinal data. R statistical and graphic functions will then treat the data appriopriately.