Using a Factor

Patient Dataset

patientID <- c(1, 2, 3, 4)
age <- c(25, 34, 28, 52)
diabetes <- c("Type1", "Type2", "Type1", "Type1")
status <- c("Poor", "Improved", "Excellent", "Poor")
diabetes <- factor(diabetes)
status <- factor(status, order=TRUE)
patientdata <- data.frame(patientID, age, diabetes, status)

Structure of the patientdata

# structure of the patientdata
str(patientdata)

## 'data.frame':    4 obs. of  4 variables:
##  $ patientID: num  1 2 3 4
##  $ age      : num  25 34 28 52
##  $ diabetes : Factor w/ 2 levels "Type1","Type2": 1 2 1 1
##  $ status   : Ord.factor w/ 3 levels "Excellent"<"Improved"<..: 3 2 1 3

Summary

# summary
summary(patientdata)

##    patientID         age         diabetes       status 
##  Min.   :1.00   Min.   :25.00   Type1:3   Excellent:1  
##  1st Qu.:1.75   1st Qu.:27.25   Type2:1   Improved :1  
##  Median :2.50   Median :31.00             Poor     :2  
##  Mean   :2.50   Mean   :34.75                          
##  3rd Qu.:3.25   3rd Qu.:38.50                          
##  Max.   :4.00   Max.   :52.00