Pandas的DataFrame數據類型

縱軸表示不同索引axis=0,橫軸表示不同列axis=1

 

 DataFrame類型創建

1.從二維ndarray對象創建

 

import pandas as pd

import numpy as np

d=pd.DataFrame(np.arange(10).reshape(2,5))

d
Out[4]: 
   0  1  2  3  4
0  0  1  2  3  4
1  5  6  7  8  9 #自動生成行索引和列索引

2.從一維ndarray對象字典創建

import pandas as pd

dt={'one':pd.Series([1,2,3],index=['a','b','c']),
'two':pd.Series([8,7,6,5],index=['a','b','c','w'])}

dt
Out[9]: 
{'one': a    1
 b    2
 c    3
 dtype: int64, 'two': a    8
 b    7
 c    6
 w    5
 dtype: int64}

d=pd.DataFrame(dt)#原字典中的鍵變成列索引值，列索引位值中的Series數據中的索引並集 18 
d
Out[11]: 
   one  two
a  1.0    8
b  2.0    7
c  3.0    6
w  NaN    5

pd.DataFrame(dt,index=['a','b','c'],columns=['two','three'])
Out[13]: 
   two three
a    8   NaN
b    7   NaN
c    6   NaN #缺少的元素會被自動補齊

3.從列表類型的字典創建

import pandas as pd

dl={'one':[1,2,3,4],'two':[3,5,6,9]}

pd.DataFrame(dl,index=['a','b','c','d']) #這里注意后加的索引值得跟字典里的值數一樣  6 Out[28]: 
   one  two
a    1    3
b    2    5
c    3    6
d    4    9