set_index
df.set_index('hiredate')
'''
eno ename dept gender salary
hiredate
2023-02-21 11 Adam 10 m 2000
2023-02-20 12 Smith 20 m 2400
2023-02-19 13 Mary 20 f 2200
2023-02-18 14 Blake 40 m 3000
2023-02-17 15 Laura 30 f 3600
'''
plot
df.plot()
상관관계 매트릭스
df.corr()
'''
YearsExperience Salary
YearsExperience 1.000000 0.978242 # 상관 관계가 매우 크다
Salary 0.978242 1.000000
'''