代码示例:
import pandas as pd
from pandas import DataFrame,Series
import numpy as np
#使用数组创建dataframe,默认行索引、默认列索引
df1 = DataFrame(np.random.randint(0,10,(3,3)))
print(df1)
'''
打印:
0 1 2
0 8 9 7
1 8 4 8
2 1 5 3
'''
#index执行行索引、columns指定列索引
df2 = DataFrame(np.random.randint(0,10,(3,3)),index=[1,2,3],columns=['q','w','e'])
print(df2)
'''
打印:
q w e
1 1 0 7
2 8 7 5
3 7 9 5
'''
#使用字典创建dataframe(行索引由index决定,列索引由字典的键决定)
city={
'Province': ['TianJin', 'Beijing', 'ShangHai', 'ChongQing','ShenZhen'],
'pop': [1.3, 2.5, 1.9, 0.7,2.1],
'year': [2019, 2019, 2019, 2019, 2019]}
df3 = DataFrame(city)
print(df3)
'''
打印:
Province pop year
0 TianJin 1.3 2019
1 Beijing 2.5 2019
2 ShangHai 1.9 2019
3 ChongQing 0.7 2019
4 ShenZhen 2.1 2019
'''
#指定index
df4 = DataFrame(city,index=['TJ','BJ','SH','CQ','SZ'])
print(df4)
'''
打印:
Province pop year
TJ TianJin 1.3 2019
BJ Beijing 2.5 2019
SH ShangHai 1.9 2019
CQ ChongQing 0.7 2019
SZ ShenZhen 2.1 2019
'''
#dataframe转字典,默认参数
dict1 = df4.to_dict()
print(dict1)
'''
打印:
{
'Province': {'TJ': 'TianJin', 'BJ': 'Beijing', 'SH': 'ShangHai', 'CQ': 'ChongQing', 'SZ': 'ShenZhen'},
'pop': {'TJ': 1.3, 'BJ': 2.5, 'SH': 1.9, 'CQ': 0.7, 'SZ': 2.1},
'year': {'TJ': 2019, 'BJ': 2019, 'SH': 2019, 'CQ': 2019, 'SZ': 2019}
}
'''
#dataframe转字典,指定orient='list' 即每一列的值以列表的形式承装
dict2 = df4.to_dict(orient='list')
print(dict2)
'''
打印:
{
'Province': ['TianJin', 'Beijing', 'ShangHai', 'ChongQing', 'ShenZhen'],
'pop': [1.3, 2.5, 1.9, 0.7, 2.1],
'year': [2019, 2019, 2019, 2019, 2019]
}
'''