#' @factor gender[male,female]
#' @factor education[none=0,highschool=1,college=2,university=3|4]
height gender education grade
154.6 male 2 D
154.1 female 1 C
149.1 male 3 B
160.7 male 3 B
167.5 female 4 A
149.2 male 4 D
160 male 0 B
155.2 female 1 B
146.9 male 0 D
161.1 female 1 A
136.9 male 4 C
161.2 female 4 B
163.2 female 1 A
170.8 female 3 A
178.7 female 3 D
168.1 male 2 A
151.6 female 0 C
152 male 2 C
151.7 male 3 A
161.5 male 0 A
155 male 4 B