numpy使用[]语法索引二维numpy数组中指定倒数范围数据行的数值内容(accessing rows in numpy array with reverse specific range)
#仿真数据
import pandas as pd
import numpy as np
pd.options.mode.chained_assignment = None
pd.set_option('display.max_columns', 100)
import matplotlib.pyplot as plt
%matplotlib inline
plt.rcParams['font.size'] = 16
data = {'产品':['肉类','盐铁','纺织','木材']*2,
'年份':[1046,1046,1046,1046,1047,1047,1047,1047],
'诸侯':['秦','齐','楚','秦','秦','楚','齐','齐'],
'产量':[180,140,300,200,150,60,80,320]}
df=pd.DataFrame(data, columns=['产品','年份','诸侯','产量'])
df