Pandas练习笔记——（三）

In [2]:
import numpy as np
import pandas as pd

In [3]:
ser = pd.Series([5,0,3,8,4],index=['red','blue','yellow','white','green'])
ser.index
 
In [21]:
ser
Out[21]:
red       5
blue      0
yellow    3
white     8
green     4
dtype: int64
In [20]:
# 更换索引时可调整标签顺序，删除或增加
ser.reindex(['white','blue','glod','red','yellow'])
 
Out[20]:
white     8.0
blue      0.0
glod      NaN
red       5.0
yellow    3.0
dtype: float64

In [23]:
 
ser3 = pd.Series([1,5,6,3],index=[0,3,5,6])
ser3
 
Out[23]:
0    1
3    5
5    6
6    3
dtype: int64

In [24]:
 
ser3.reindex(range(6),method='ffill')
 
Out[24]:
0    1
1    1
2    1
3    5
4    5
5    6
dtype: int64
In [25]:
ser3.reindex(range(7),method='bfill')

Out[25]:
0    1
1    5
2    5
3    5
4    6
5    6
6    3
dtype: int64
In [29]:
ser.drop(['red','white'])
 
Out[29]:
blue      0
yellow    3
green     4
dtype: int64
In [33]:
frame = pd.DataFrame(np.arange(16).reshape((4,4)),index=['red','blue','yellow','white'],columns=['ball','pen','pencil','paper'])
frame
 
Out[33]:
     ball    pen    pencil    paper
red    0    1    2    3
blue    4    5    6    7
yellow    8    9    10    11
white    12    13    14    15
In [34]:
 
ser = pd.Series(np.arange(4),index=['ball','pen','pencil','paper'])
ser
 
Out[34]:
ball      0
pen       1
pencil    2
paper     3
dtype: int32
In [35]:
 
frame - ser
 
Out[35]:
     ball    pen    pencil    paper
red    0    0    0    0
blue    4    4    4    4
yellow    8    8    8    8
white    12    12    12    12
In [37]:
 
ser['boll'] = 9
ser
 
Out[37]:
ball      0
pen       1
pencil    2
paper     3
boll      9
dtype: int64
In [38]:
frame - ser
 
 
Out[38]:
     ball    boll    paper    pen    pencil
red    0    NaN    0    0    0
blue    4    NaN    4    4    4
yellow    8    NaN    8    8    8
white    12    NaN    12    12    12
In [39]:
np.sqrt(frame)
 
 
Out[39]:
     ball    pen    pencil    paper
red    0.000000    1.000000    1.414214    1.732051
blue    2.000000    2.236068    2.449490    2.645751
yellow    2.828427    3.000000    3.162278    3.316625
white    3.464102    3.605551    3.741657    3.872983


In [40]:
 
f =  lambda x : x.max() - x.min()
# 调用函数
frame.apply(f)
 
 
Out[40]:
ball      12
pen       12
pencil    12
paper     12
dtype: int64
In [43]:

frame.apply(f,axis=1)

Out[43]:
red       3
blue      3
yellow    3
white     3
dtype: int64
In [44]:
 
# 也可以返回Series对象
def f(x):
    return pd.Series([x.min(),x.max()],index=['min','max'])
​
frame.apply(f)
 
Out[44]:
     ball    pen    pencil    paper
min    0    1    2    3
max    12    13    14    15
In [46]:
 
frame.sum(axis=1)
 
Out[46]:
red        6
blue      22
yellow    38
white     54
dtype: int64
In [47]:

frame.mean()
 
Out[47]:
ball      6.0
pen       7.0
pencil    8.0
paper     9.0
dtype: float64
In [50]:
 
frame.describe()
 
 
Out[50]:
     ball    pen    pencil    paper
count    4.000000    4.000000    4.000000    4.000000
mean    6.000000    7.000000    8.000000    9.000000
std    5.163978    5.163978    5.163978    5.163978
min    0.000000    1.000000    2.000000    3.000000
25%    3.000000    4.000000    5.000000    6.000000
50%    6.000000    7.000000    8.000000    9.000000
75%    9.000000    10.000000    11.000000    12.000000
max    12.000000    13.000000    14.000000    15.000000
 

In [52]:
ser = pd.Series([5,0,3,8,4],index=['red','blue','yellow','whiite','green'])
ser
 
Out[52]:
red       5
blue      0
yellow    3
whiite    8
green     4
dtype: int64
In [53]:
 
# 按照首字母升序
ser.sort_index()
 
 
Out[53]:
blue      0
green     4
red       5
whiite    8
yellow    3
dtype: int64
In [54]:
ser.sort_index(ascending=False)
 
Out[54]:
yellow    3
whiite    8
red       5
green     4
blue      0
dtype: int64
In [55]:
 
frame = pd.DataFrame(np.arange(16).reshape((4,4)),index=['red','blue','yellow','white'],columns=['ball','pen','pencil','paper'])
frame
 
 
Out[55]:
     ball    pen    pencil    paper
red    0    1    2    3
blue    4    5    6    7
yellow    8    9    10    11
white    12    13    14    15
In [56]:
 
frame.sort_index(axis=1)
 
 
Out[56]:
     ball    paper    pen    pencil
red    0    3    1    2
blue    4    7    5    6
yellow    8    11    9    10
white    12    15    13    14
In [66]:
 
frame.sort_index(by=['pen','paper'])
D:\ProgramData\Anaconda3\lib\site-packages\ipykernel_launcher.py:1: FutureWarning: by argument to sort_index is deprecated, pls use .sort_values(by=...)
  """Entry point for launching an IPython kernel.
Out[66]:
     ball    pen    pencil    paper
red    0    1    2    3
blue    4    5    6    7
yellow    8    9    10    11
white    12    13    14    15
In [67]:

ser.rank()
 
Out[67]:
red       4.0
blue      1.0
yellow    2.0
whiite    5.0
green     3.0
dtype: float64
In [68]:
ser.rank(method='first')
 
 
Out[68]:
red       4.0
blue      1.0
yellow    2.0
whiite    5.0
green     3.0
dtype: float64

In [69]:

ser.rank(ascending=False)
 
 
Out[69]:
red       2.0
blue      5.0
yellow    4.0
whiite    1.0
green     3.0
dtype: float64