decision tree

# csv 파일을 읽어서 데이터 프레임 생성> credit str(credit)'data.frame': 1000 obs. of 17 variables:$checking_balance : Factor w/ 4 levels " 200 DM",..: 1 3 4 1 1 4 4 3 4 3 ...$ months_loan_duration: int 6 48 12 42 24 36 24 36 12 30 ...$credit_history : Factor w/ 5 levels "critical","good",..: 1 2 1 2 4 2 2 2 2 1 ...$ purpose : Factor w/ 6 levels "business","car",..: 5 5 4 5 2 4 5 2 5 2 ...$ amount ..