combine_rare_levels {regclass} | R Documentation |
Combines rare levels of a categorical variable
Description
This function takes a categorical variable and combines all levels with frequencies less than a user-specified threshold named Combined
Usage
combine_rare_levels(x,threshold=20,newname="Combined")
Arguments
x |
a vector of categorical values |
threshold |
levels that appear a total of |
newname |
defaults to |
Details
Returns a list of two objects:
values
- The recoded values of the categorical variable. All levels which appeared threshold
times or fewer are now known as Combined
combined
- The levels that have been combined together
If, after being combined, the newname
level has threshold
or fewer instances, the remaining level that appears least often is combined as well.
Author(s)
Adam Petrie
References
Introduction to Regression and Modeling
Examples
data(EX6.CLICK)
x <- EX6.CLICK[,15]
table(x)
#Combine all levels which appear 700 or fewer times (AA, CC, DD)
y <- combine_rare_levels(x,700)
table( y$values )
#Combine all levels which appear 1350 or fewer times. This forces BB (which
#occurs 2422 times) into the Combined level since the three levels that appear
#fewer than 1350 times do not appear more than 1350 times combined
y <- combine_rare_levels(x,1350)
table( y$values )