dataframe创建

import numpy as np
import pandas as pd
#创建方法一：多个series组成字典创建dataframe
pp = {‘bj‘:3000,‘gz‘:2800,‘sh‘:3200}
area={‘bj‘:290,‘gz‘:310,‘sh‘:150}
pp_series = pd.Series(pp)
area_series = pd.Series(area)
citys = pd.DataFrame({‘area‘:area_series,‘population‘:pp_series})
print(citys)
print(‘-‘*50)

#创建方法二：多个列表组成字典创建dataframe
data1 = {‘a‘:[1,2,3],
        ‘b‘:[3,4,5],
        ‘c‘:[5,6,7]}
data=pd.DataFrame(data1)
print(data)
print(‘-‘*50)

#创建方法三：多个series组成列表 指定index
citys = pd.DataFrame([area_series, pp_series],index=[‘population‘,‘area‘])
print(citys)
print(‘-‘*50)

#一个Series指定columns
data = pd.DataFrame(pp_series, columns=[‘population‘])
print(data)
print(‘-‘*50)

#创建方式四：用二维数组，指定index和column
a = np.arange(12).reshape(3,4)
data = pd.DataFrame(a, index = list(‘abc‘), columns=list(‘ABCD‘))
print(data)